text: /*
  
      morphic.js
  
      a lively Web-GUI
      inspired by Squeak
  
      written by Jens Mönig
      jens@moenig.org
  
      Copyright (C) 2018 by Jens Mönig
  
      This file is part of Snap!.
  
      Snap! is free software: you can redistribute it and/or modify
      it under the terms of the GNU Affero General Public License as
      published by the Free Software Foundation, either version 3 of
      the License, or (at your option) any later version.
  
      This program is distributed in the hope that it will be useful,
      but WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      GNU Affero General Public License for more details.
  
      You should have received a copy of the GNU Affero General Public License
      along with this program.  If not, see <http://www.gnu.org/licenses/>.
  
  
      documentation contents
      ----------------------
      I. inheritance hierarchy
      II. object definition toc
      III. yet to implement
      IV. open issues
      V. browser compatibility
      VI. the big picture
      VII. programming guide
          (1) setting up a web page
              (a) single world
              (b) multiple worlds
              (c) an application
          (2) manipulating morphs
          (3) events
              (a) mouse events
              (b) context menu
              (c) dragging
              (d) dropping
              (e) keyboard events
              (f) resize event
              (g) combined mouse-keyboard events
              (h) text editing events
          (4) stepping
          (5) creating new kinds of morphs
          (6) development and user modes
          (7) turtle graphics
          (8) damage list housekeeping
          (9) supporting high-resolution "retina" screens
          (10 animations
          (11) minifying morphic.js
      VIII. acknowledgements
      IX. contributors
  
  
      I. hierarchy
      -------------
      the following tree lists all constructors hierarchically,
      indentation indicating inheritance. Refer to this list to get a
      contextual overview:
  
      Animation
      Color
      Node
          Morph
              BlinkerMorph
                  CursorMorph
              BouncerMorph*
              BoxMorph
                  InspectorMorph
                  MenuMorph
                  MouseSensorMorph*
                  SpeechBubbleMorph
              CircleBoxMorph
                  SliderButtonMorph
                  SliderMorph
              ColorPaletteMorph
                  GrayPaletteMorph
              ColorPickerMorph
              FrameMorph
                  ScrollFrameMorph
                      ListMorph
                  StringFieldMorph
                  WorldMorph
              HandleMorph
              HandMorph
              PenMorph
              ShadowMorph
              StringMorph
              TextMorph
              TriggerMorph
                  MenuItemMorph
      Point
      Rectangle
  
  
      II. toc
      -------
      the following list shows the order in which all constructors are
      defined. Use this list to locate code in this document:
  
      Global settings
      Global functions
  
      Animation
      Color
      Point
      Rectangle
      Node
      Morph
      ShadowMorph
      HandleMorph
      PenMorph
      ColorPaletteMorph
      GrayPaletteMorph
      ColorPickerMorph
      BlinkerMorph
      CursorMorph
      BoxMorph
      SpeechBubbleMorph
      CircleBoxMorph
      SliderButtonMorph
      SliderMorph
      MouseSensorMorph*
      InspectorMorph
      MenuMorph
      StringMorph
      TextMorph
      TriggerMorph
      MenuItemMorph
      FrameMorph
      ScrollFrameMorph
      ListMorph
      StringFieldMorph
      BouncerMorph*
      HandMorph
      WorldMorph
  
      * included only for demo purposes
  
  
      III. yet to implement
      ---------------------
      - keyboard support for scroll frames and lists
      - full keyboard support for menus (partial support exists)
      - virtual keyboard support for Android and IE
  
  
      IV. open issues
      ----------------
      - clipboard support (copy & paste) for non-textual data
  
  
      V. browser compatibility
      ------------------------
      I have taken great care and considerable effort to make morphic.js
      runnable and appearing exactly the same on all current browsers
      available to me:
  
      - Firefox for Windows
      - Firefox for Mac
      - Firefox for Android
      - Chrome for Windows
      - Chrome for Mac
      - Chrome for Android
      - Safari for Windows (deprecated)
      - safari for Mac
      - Safari for iOS (mobile)
      - IE for Windows
      - Edge for Windows
      - Opera for Windows
      - Opera for Mac
  
  
      VI. the big picture
      -------------------
      Morphic.js is completely based on Canvas and JavaScript, it is just
      Morphic, nothing else. Morphic.js is very basic and covers only the
      bare essentials:
  
          * a stepping mechanism (a time-sharing multiplexer for lively
            user interaction ontop of a single OS/browser thread)
          * progressive display updates (only dirty rectangles are
            redrawn in each display cycle)
          * a tree structure
          * a single World per Canvas element (although you can have
            multiple worlds in multiple Canvas elements on the same web
            page)
          * a single Hand per World (but you can support multi-touch
            events)
          * a single text entry focus per World
  
      In its current state morphic.js doesn't support Transforms (you
      cannot rotate Morphs), but with PenMorph there already is a simple
      LOGO-like turtle that you can use to draw onto any Morph it is
      attached to. I'm planning to add special Morphs that support these
      operations later on, but not for every Morph in the system.
      Therefore these additions ("sprites" etc.) are likely to be part of
      other libraries ("microworld.js") in separate files.
  
      the purpose of morphic.js is to provide a malleable framework that
      will let me experiment with lively GUIs for my hobby horse, which
      is drag-and-drop, blocks based programming languages. Those things
      (BYOB4 - http://byob.berkeley.edu) will be written using morphic.js
      as a library.
  
  
      VII. programming guide
      ----------------------
      Morphic.js provides a library for lively GUIs inside single HTML
      Canvas elements. Each such canvas element functions as a "world" in
      which other visible shapes ("morphs") can be positioned and
      manipulated, often directly and interactively by the user. Morphs
      are tree nodes and may contain any number of submorphs ("children").
  
      All things visible in a morphic World are morphs themselves, i.e.
      all text rendering, blinking cursors, entry fields, menus, buttons,
      sliders, windows and dialog boxes etc. are created with morphic.js
      rather than using HTML DOM elements, and as a consequence can be
      changed and adjusted by the programmer regardless of proprietary
      browser behavior.
  
      Each World has an - invisible - "Hand" resembling the mouse cursor
      (or the user's finger on touch screens) which handles mouse events,
      and may also have a keyboardReceiver to handle key events.
  
      The basic idea of Morphic is to continuously run display cycles and
      to incrementally update the screen by only redrawing those  World
      regions    which have been "dirtied" since the last redraw. Before
      each shape is processed for redisplay it gets the chance to perform
      a "step" procedure, thus allowing for an illusion of concurrency.
  
  
      (1) setting up a web page
      -------------------------
      Setting up a web page for Morphic always involves three steps:
      adding one or more Canvas elements, defining one or more worlds,
      initializing and starting the main loop.
  
  
      (a) single world
      -----------------
      Most commonly you will want your World to fill the browsers's whole
      client area. This default situation is easiest and most straight
      forward.
  
      example html file:
  
      <!DOCTYPE html>
      <html>
          <head>
              <title>Morphic!</title>
              <script type="text/javascript" src="morphic.js"></script>
              <script type="text/javascript">
                  var world;
  
                  window.onload = function () {
                      world = new WorldMorph(
                          document.getElementById('world'));
                      loop();
                  };
  
                  function loop() {
                      requestAnimationFrame(loop);
                      world.doOneCycle();
                  }
              </script>
          </head>
          <body>
              <canvas id="world" tabindex="1" width="800" height="600">
                  <p>Your browser doesn't support canvas.</p>
              </canvas>
          </body>
      </html>
  
      if you use ScrollFrames or otherwise plan to support mouse wheel
      scrolling events, you might also add the following inline-CSS
      attribute to the Canvas element:
  
          style="position: absolute;"
  
      which will prevent the World to be scrolled around instead of the
      elements inside of it in some browsers.
  
  
      (b) multiple worlds
      -------------------
      If you wish to create a web page with more than one world, make
      sure to prevent each world from auto-filling the whole page and
      include    it in the main loop. It's also a good idea to give each
      world its own tabindex:
  
      example html file:
  
      <!DOCTYPE html>
      <html>
          <head>
              <title>Morphic!</title>
              <script type="text/javascript" src="morphic.js"></script>
              <script type="text/javascript">
                  var world1, world2;
  
                  window.onload = function () {
                      world1 = new WorldMorph(
                          document.getElementById('world1'), false);
                      world2 = new WorldMorph(
                          document.getElementById('world2'), false);
                      loop();
                  };
  
                  function loop() {
                      requestAnimationFrame(loop);
                      world1.doOneCycle();
                      world2.doOneCycle();
                  }
              </script>
          </head>
          <body>
              <p>first world:</p>
              <canvas id="world1" tabindex="1" width="600" height="400">
                  <p>Your browser doesn't support canvas.</p>
              </canvas>
              <p>second world:</p>
              <canvas id="world2" tabindex="2" width="400" height="600">
                  <p>Your browser doesn't support canvas.</p>
              </canvas>
          </body>
      </html>
  
  
      (c) an application
      -------------------
      Of course, most of the time you don't want to just plain use the
      standard Morphic World "as is" out of the box, but write your own
      application (something like Scratch!) in it. For such an
      application you'll create your own morph prototypes, perhaps
      assemble your own "window frame" and bring it all to life in a
      customized World state. the following example creates a simple
      snake-like mouse drawing game.
  
      example html file:
  
      <!DOCTYPE html>
      <html>
          <head>
              <title>touch me!</title>
              <script type="text/javascript" src="morphic.js"></script>
              <script type="text/javascript">
                  var worldCanvas, sensor;
  
                  window.onload = function () {
                      var x, y, w, h;
  
                      worldCanvas = document.getElementById('world');
                      world = new WorldMorph(worldCanvas);
                      world.isDevMode = false;
                      world.color = new Color();
  
                      w = 100;
                      h = 100;
  
                      x = 0;
                      y = 0;
  
                      while ((y * h) < world.height()) {
                          while ((x * w) < world.width()) {
                              sensor = new MouseSensorMorph();
                              sensor.setPosition(new Point(x * w, y * h));
                              sensor.alpha = 0;
                              sensor.setExtent(new Point(w, h));
                              world.add(sensor);
                              x += 1;
                          }
                          x = 0;
                          y += 1;
                      }
                      loop();
                  };
  
                  function loop() {
                      requestAnimationFrame(loop);
                      world.doOneCycle();
                  }
              </script>
          </head>
          <body bgcolor='black'>
              <canvas id="world" width="800" height="600">
                  <p>Your browser doesn't support canvas.</p>
              </canvas>
          </body>
      </html>
  
      To get an idea how you can craft your own custom morph prototypes
      I've included two examples which should give you an idea how to add
      properties, override inherited methods and use the stepping
      mechanism for "livelyness":
  
          BouncerMorph
          MouseSensorMorph
  
      For the sake of sharing a single file I've included those examples
      in morphic.js itself. Usually you'll define your additions in a
      separate file and keep morphic.js untouched.
  
  
      (2) manipulating morphs
      -----------------------
      There are many methods to programmatically manipulate morphs. Among
      the most important and common ones among all morphs are the
      following nine:
  
      * hide()
      * show()
  
      * setPosition(aPoint)
      * setExtent(aPoint)
      * setColor(aColor)
  
      * add(submorph)            - attaches submorph ontop
      * addBack(submorph)        - attaches submorph underneath
  
      * fullCopy()               - duplication
      * destroy()                - deletion
  
  
      (3) events
      ----------
      All user (and system) interaction is triggered by events, which are
      passed on from the root element - the World - to its submorphs. The
      World contains a list of system (browser) events it reacts to in its
  
          initEventListeners()
  
      method. Currently there are
  
          - mouse
          - drop
          - keyboard
          - (window) resize
  
      events.
  
      These system events are dispatched within the morphic World by the
      World's Hand and its keyboardReceiver (usually the active text
      cursor).
  
  
      (a) mouse events:
      -----------------
      The Hand dispatches the following mouse events to relevant morphs:
  
          mouseDownLeft
          mouseDownRight
          mouseClickLeft
          mouseClickRight
          mouseDoubleClick
          mouseEnter
          mouseLeave
          mouseEnterDragging
          mouseLeaveDragging
          mouseMove
          mouseScroll
  
      If you wish your morph to react to any such event, simply add a
      method of the same name as the event, e.g:
  
          MyMorph.prototype.mouseMove = function(pos) {};
  
      All of these methods have as optional parameter a Point object
      indicating the current position of the Hand inside the World's
      coordinate system. The
  
          mouseMove(pos, button)
  
      event method has an additional optional parameter indicating the
      currently pressed mouse button, which is either 'left' or 'right'.
      You can use this to let users interact with 3D environments.
  
      Events may be "bubbled" up a morph's owner chain by calling
  
          this.escalateEvent(functionName, arg)
  
      in the event handler method's code.
  
      Likewise, removing the event handler method will render your morph
      passive to the event in question.
  
  
      (b) context menu:
      -----------------
      By default right-clicking (or single-finger tap-and-hold) on a morph
      also invokes its context menu (in addition to firing the
      mouseClickRight event). A morph's context menu can be customized by
      assigning a Menu instance to its
  
          customContextMenu
  
      property, or altogether suppressed by overriding its inherited
  
          contextMenu()
  
      method.
  
  
      (c) dragging:
      -------------
      Dragging a morph is initiated when the left mouse button is pressed,
      held and the mouse is moved.
  
      You can control whether a morph is draggable by setting its
  
          isDraggable
  
      property either to false or true. If a morph isn't draggable itself
      it will pass the pick-up request up its owner chain. This lets you
      create draggable composite morphs like Windows, DialogBoxes,
      Sliders etc.
  
      Sometimes it is desireable to make "template" shapes which cannot be
      moved themselves, but from which instead duplicates can be peeled
      off. This is especially useful for building blocks in construction
      kits, e.g. the MIT-Scratch palette. Morphic.js lets you control this
      functionality by setting the
  
          isTemplate
  
      property flag to true for any morph whose "isDraggable" property is
      turned off. When dragging such a Morph the hand will instead grab
      a duplicate of the template whose "isDraggable" flag is true and
      whose "isTemplate" flag is false, in other words: a non-template.
  
      When creating a copy from a template, the copy's
  
          reactToTemplateCopy
  
      is invoked, if it is present.
  
      Dragging is indicated by adding a drop shadow to the morph in hand.
      If a morph follows the hand without displaying a drop shadow it is
      merely being moved about without changing its parent (owner morph),
      e.g. when "dragging" a morph handle to resize its owner, or when
      "dragging" a slider button.
  
      Right before a morph is picked up its
  
          selectForEdit
  
      and
  
          prepareToBeGrabbed(handMorph)
  
      methods are invoked, each if it is present. the optional
  
          selectForEdit
  
      if implemented, must return the object that is to be picked up.
      In addition to just returning the original object chosen by the user
      your method can also modify the target's environment and instead return
      a copy of the selected morph if, for example, you would like to implement
      a copy-on-write mechanism such as in Snap.
  
      Immediately after the pick-up the former parent's
  
          reactToGrabOf(grabbedMorph)
  
      method is called, again only if it exists.
  
      Similar to events, these  methods are optional and don't exist by
      default. For a simple example of how they can be used to adjust
      scroll bars in a scroll frame please have a look at their
      implementation in FrameMorph.
  
  
      (d) dropping:
      -------------
      Dropping is triggered when the left mouse button is either pressed
      or released while the Hand is dragging a morph.
  
      Dropping a morph causes it to become embedded in a new owner morph.
      You can control this embedding behavior by setting the prospective
      drop target's
  
          acceptsDrops
  
      property to either true or false, or by overriding its inherited
  
          wantsDropOf(aMorph)
  
      method.
  
      Right before dropping a morph the designated new parent's optional
  
          selectForEdit
  
      method is invoked if it is present. Again, if implemented this method
      must return the new parent for the morph that is about to be dropped.
      Again, in addition to just returning the designeted drop-target
      your method can also modify its environment and instead return
      a copy of the new parent if, for example, you would like to implement
      a copy-on-write mechanism such as in Snap.
  
      Right after a morph has been dropped its
  
          justDropped(handMorph)
  
      method is called, and its new parent's
  
          reactToDropOf(droppedMorph, handMorph)
  
      method is invoked, again only if each method exists.
  
      Similar to events, these  methods are optional and by default are
      not present in morphs by default (watch out for inheritance,
      though!). For a simple example of how they can be used to adjust
      scroll bars in a scroll frame please have a look at their
      implementation in FrameMorph.
  
      Drops of image elements from outside the world canvas are dispatched as
  
          droppedImage(aCanvas, name)
          droppedSVG(anImage, name)
  
      events to interested Morphs at the mouse pointer. If you want you Morph
      to e.g. import outside images you can add the droppedImage() and / or the
      droppedSVG() methods to it. The parameter passed to the event handles is
      a new offscreen canvas element representing a copy of the original image
      element which can be directly used, e.g. by assigning it to another
      Morph's image property. In the case of a dropped SVG it is an image
      element (not a canvas), which has to be rasterized onto a canvas before
      it can be used. The benefit of handling SVGs as image elements is that
      rasterization can be deferred until the destination scale is known, taking
      advantage of SVG's ability for smooth scaling. If instead SVGs are to be
      rasterized right away, you can set the
  
          MorphicPreferences.rasterizeSVGs
  
      preference to <true>. In this case dropped SVGs also trigger the
      droppedImage() event with a canvas containing a rasterized version of the
      SVG.
  
      The same applies to drops of audio or text files from outside the world
      canvas.
  
      Those are dispatched as
  
          droppedAudio(anAudio, name)
          droppedText(aString, name)
  
      events to interested Morphs at the mouse pointer.
  
      if none of the above content types can be determined, the file contents
      is dispatched as an ArrayBuffer to interested Morphs:
  
          droppedBinary(anArrayBuffer, name)
  
  
      (e) keyboard events
      -------------------
      The World dispatches the following key events to its active
      keyboardReceiver:
  
          keypress
          keydown
          keyup
  
      Currently the only morph which acts as keyboard receiver is
      CursorMorph, the basic text editing widget. If you wish to add
      keyboard support to your morph you need to add event handling
      methods for
  
          processKeyPress(event)
          processKeyDown(event)
          processKeyUp(event)
  
      and activate them by assigning your morph to the World's
  
          keyboardReceiver
  
      property.
  
      Note that processKeyUp() is optional and doesn't have to be present
      if your morph doesn't require it.
  
  
      (f) resize event
      ----------------
      The Window resize event is handled by the World and allows the
      World's extent to be adjusted so that it always completely fills
      the browser's visible page. You can turn off this default behavior
      by setting the World's
  
          useFillPage
  
      property to false.
  
      Alternatively you can also initialize the World with the
      useFillPage switch turned off from the beginning by passing the
      false value as second parameter to the World's constructor:
  
          world = new World(aCanvas, false);
  
      Use this when creating a web page with multiple Worlds.
  
      if "useFillPage" is turned on the World dispatches an
  
          reactToWorldResize(newBounds)
  
      events to all of its children (toplevel only), allowing each to
      adjust to the new World bounds by implementing a corresponding
      method, the passed argument being the World's new dimensions after
      completing the resize. By default, the "reactToWorldResize" Method
      does not exist.
  
      Example:
  
      Add the following method to your Morph to let it automatically
      fill the whole World, but leave a 10 pixel border uncovered:
  
          MyMorph.prototype.reactToWorldResize = function (rect) {
              this.changed();
              this.bounds = rect.insetBy(10);
              this.drawNew();
              this.changed();
          };
  
  
      (g) combined mouse-keyboard events
      ----------------------------------
      Occasionally you'll want an object to react differently to a mouse
      click or to some other mouse event while the user holds down a key
      on the keyboard. Such "shift-click", "ctl-click", or "alt-click"
      events can be implemented by querying the World's
  
          currentKey
  
      property inside the function that reacts to the mouse event. This
      property stores the keyCode of the key that's currently pressed.
      Once the key is released by the user it reverts to null.
  
  
      (h) text editing events
      -----------------------
      Much of Morphic's "liveliness" comes out of allowing text elements
      (instances of either single-lined StringMorph or multi-lined TextMorph)
      to be directly manipulated and edited by users. This requires other
      objects which may have an interest in the text element's state to react
      appropriately. Therefore text elements and their manipulators emit
      a stream of events, mostly by "bubbling" them up the text element's
      owner chain. Text elements' parents are notified about the following
      events:
  
      Whenever the user presses a key on the keyboard while a text element
      is being edited, a
  
          reactToKeystroke(event)
  
      is escalated up its parent chain, the "event" parameter being the
      original one received by the World.
  
      Once the user has completed the edit, the following events are
      dispatched:
  
          accept() - <enter> was pressed on a single line of text
          cancel() - <esc> was pressed on any text element
  
      Note that "accept" only gets triggered by single-line texte elements,
      as the <enter> key is used to insert line breaks in multi-line
      elements. Therefore, whenever a text edit is terminated by the user
      (accepted, cancelled or otherwise),
  
          reactToEdit(StringOrTextMorph)
  
      is triggered.
  
      If the MorphicPreference's
  
          useSliderForInput
  
      setting is turned on, a slider is popped up underneath the currently
      edited text element letting the user insert numbers out of the given
      slider range. Whenever this happens, i.e. whenever the slider is moved
      or while the slider button is pressed, a stream of
  
          reactToSliderEdit(StringOrTextMorph)
  
      events is dispatched, allowing for "Bret-Victor" style "live coding"
      applications.
  
      In addition to user-initiated events text elements also emit
      change notifications to their direct parents whenever their drawNew()
      method is invoked. That way complex Morphs containing text elements
      get a chance to react if something about the embedded text has been
      modified programmatically. These events are:
  
          layoutChanged() - sent from instances of TextMorph
          fixLayout() - sent from instances of StringMorph
  
      they are different so that Morphs which contain both multi-line and
      single-line text elements can hold them apart.
  
  
      (4) stepping
      ------------
      Stepping is what makes Morphic "magical". Two properties control
      a morph's stepping behavior: the fps attribute and the step()
      method.
  
      By default the
  
          step()
  
      method does nothing. As you can see in the examples of BouncerMorph
      and MouseSensorMorph you can easily override this inherited method
      to suit your needs.
  
      By default the step() method is called once per display cycle.
      Depending on the number of actively stepping morphs and the
      complexity of your step() methods this can cause quite a strain on
      your CPU, and also result in your application behaving differently
      on slower computers than on fast ones.
  
      setting
  
          myMorph.fps
  
      to a number lower than the interval for the main loop lets you free
      system resources (albeit at the cost of a less responsive or slower
      behavior for this particular morph).
  
  
      (5) creating new kinds of morphs
      --------------------------------
      The real fun begins when you start to create new kinds of morphs
      with customized shapes. Imagine, e.g. jigsaw puzzle pieces or
      musical notes. For this you have to override the default
  
          drawNew()
  
      method.
  
      This method creates a new offscreen Canvas and stores it in
      the morph's
  
          image
  
      property.
  
      Use the following template for a start:
  
          MyMorph.prototype.drawNew = function() {
              var context;
              this.image = newCanvas(this.extent());
              context = this.image.getContext('2d');
              // use context to paint stuff here
          };
  
      If your new morph stores or references to other morphs outside of
      the submorph tree in other properties, be sure to also override the
      default
  
          updateReferences()
  
      method if you want it to support duplication.
  
  
      (6) development and user modes
      ------------------------------
      When working with Squeak on Scratch or BYOB among the features I
      like the best and use the most is inspecting what's going on in
      the World while it is up and running. That's what development mode
      is for (you could also call it debug mode). In essence development
      mode controls which context menu shows up. In user mode right
      clicking (or double finger tapping) a morph invokes its
  
          customContextMenu
  
      property, whereas in development mode only the general
  
          developersMenu()
  
      method is called and the resulting menu invoked. The developers'
      menu features Gui-Builder-wise functionality to directly inspect,
      take apart, reassamble and otherwise manipulate morphs and their
      contents.
  
      Instead of using the "customContextMenu" property you can also
      assign a more dynamic contextMenu by overriding the general
  
          userMenu()
  
      method with a customized menu constructor. The difference between
      the customContextMenu property and the userMenu() method is that
      the former is also present in development mode and overrides the
      developersMenu() result. For an example of how to use the
      customContextMenu property have a look at TextMorph's evaluation
      menu, which is used for the Inspector's evaluation pane.
  
      When in development mode you can inspect every Morph's properties
      with the inspector, including all of its methods. The inspector
      also lets you add, remove and rename properties, and even edit
      their values at runtime. Like in a Smalltalk environment the inspect
      features an evaluation pane into which you can type in arbitrary
      JavaScript code and evaluate it in the context of the inspectee.
  
      Use switching between user and development modes while you are
      developing an application and disable switching to development once
      you're done and deploying, because generally you don't want to
      confuse end-users with inspectors and meta-level stuff.
  
  
      (7) turtle graphics
      -------------------
  
      The basic Morphic kernel features a simple LOGO turtle constructor
      called
  
          PenMorph
  
      which you can use to draw onto its parent Morph. By default every
      Morph in the system (including the World) is able to act as turtle
      canvas and can display pen trails. Pen trails will be lost whenever
      the trails morph (the pen's parent) performs a "drawNew()"
      operation. If you want to create your own pen trails canvas, you
      may wish to modify its
  
          penTrails()
  
      property, so that it keeps a separate offscreen canvas for pen
      trails (and doesn't loose these on redraw).
  
      the following properties of PenMorph are relevant for turtle
      graphics:
  
          color        - a Color
          size        - line width of pen trails
          heading        - degrees
          isDown        - drawing state
  
      the following commands can be used to actually draw something:
  
          up()        - lift the pen up, further movements leave no trails
          down()        - set down, further movements leave trails
          clear()        - remove all trails from the current parent
          forward(n)    - move n steps in the current direction (heading)
          turn(n)        - turn right n degrees
  
      Turtle graphics can best be explored interactively by creating a
      new PenMorph object and by manipulating it with the inspector
      widget.
  
      NOTE: PenMorph has a special optimization for recursive operations
      called
  
          warp(function)
  
      You can significantly speed up recursive ops and increase the depth
      of recursion that's displayable by wrapping WARP around your
      recursive function call:
  
      example:
  
          myPen.warp(function () {
              myPen.tree(12, 120, 20);
          })
  
      will be much faster than just invoking the tree function, because it
      prevents the parent's parent from keeping track of every single line
      segment and instead redraws the outcome in a single pass.
  
  
      (8) damage list housekeeping
      ----------------------------
      Morphic's progressive display update comes at the cost of having to
      cycle through a list of "broken rectangles" every display cycle. If
      this list gets very long working this damage list can lead to a
      seemingly dramatic slow-down of the Morphic system. Typically this
      occurs when updating the layout of complex Morphs with very many
      submorphs, e.g. when resizing an inspector window.
  
      An effective strategy to cope with this is to use the inherited
  
          trackChanges
  
      property of the Morph prototype for damage list housekeeping.
  
      The trackChanges property of the Morph prototype is a Boolean switch
      that determines whether the World's damage list ('broken' rectangles)
      tracks changes. By default the switch is always on. If set to false
      changes are not stored. This can be very useful for housekeeping of
      the damage list in situations where a large number of (sub-) morphs
      are changed more or less at once. Instead of keeping track of every
      single submorph's changes tremendous performance improvements can be
      achieved by setting the trackChanges flag to false before propagating
      the layout changes, setting it to true again and then storing the full
      bounds of the surrounding morph. As an example refer to the
  
          moveBy()
  
      method of HandMorph, and to the
  
          fixLayout()
  
      method of InspectorMorph, or the
  
          startLayout()
          endLayout()
  
      methods of SyntaxElementMorph in the Snap application.
  
  
      (9) supporting high-resolution "retina" screens
      -----------------------------------------------
      By default retina support gets installed when Morphic.js loads. There
      are two global functions that let you test for retina availability:
  
          isRetinaSupported() - Bool, answers if retina support is available
          isRetinaEnabled()   - Bool, answers if currently in retina mode
  
      and two more functions that let you control retina support if it is
      available:
  
          enableRetinaSupport()
          disableRetinaSupport()
  
      Both of these internally test whether retina is available, so they are
      safe to call directly. For an example how to make retina support
      user-specifiable refer to
  
          Snap! >> guis.js >> toggleRetina()
  
      Even when in retina mode it often makes sense to use normal-resolution
      canvasses for simple shapes in order to save system resources and
      optimize performance. Examples are costumes and backgrounds in Snap.
      In Morphic you can create new canvas elements using
      
          newCanvas(extentPoint [, nonRetinaFlag])
  
      If retina support is enabled such new canvasses will automatically be
      high-resolution canvasses, unless the newCanvas() function is given an
      otherwise optional second Boolean <true> argument that explicitly makes
      it a non-retina canvas.
  
      Not the whole canvas API is supported by Morphic's retina utilities.
      Especially if your code uses putImageData() you will want to "downgrade"
      a target high-resolution canvas to a normal-resolution ("non-retina")
      one before using
  
          normalizeCanvas(aCanvas [, copyFlag])
  
      This will change the target canvas' resolution in place (!). If you
      pass in the optional second Boolean <true> flag the function returns
      a non-retina copy and leaves the target canvas unchanged. An example
      of this normalize mechanism is converting the penTrails layer of Snap's
      stage (high-resolution) into a sprite-costume (normal resolution).
  
  
      (10) animations
      ---------------
      Animations handle gradual transitions between one state and another over a
      period of time. Transition effects can be specified using easing functions.
      An easing function maps a fraction of the transition time to a fraction of
      the state delta. This way accelerating / decelerating and bouncing sliding
      effects can be accomplished.
  
      Animations are generic and not limited to motion, i.e. they can also handle
      other transitions such as color changes, transparency fadings, growing,
      shrinking, turning etc.
  
      Animations need to be stepped by a scheduler, e. g. an interval function.
      In Morphic the preferred way to run an animation is to register it with
      the World by adding it to the World's animation queue. The World steps each
      registered animation once per display cycle independently of the Morphic
      stepping mechanism.
  
      For an example how to use animations look at how the Morph's methods
      
          glideTo()
          fadeTo()
  
      and
      
          slideBackTo()
  
      are implemented.
  
  
      (11) minifying morphic.js
      -------------------------
      Coming from Smalltalk and being a Squeaker at heart I am a huge fan
      of browsing the code itself to make sense of it. Therefore I have
      included this documentation and (too little) inline comments so all
      you need to get going is this very file.
  
      Nowadays with live streaming HD video even on mobile phones 250 KB
      shouldn't be a big strain on bandwith, still minifying and even
      compressing morphic.js down do about 100 KB may sometimes improve
      performance in production use.
  
      Being an attorney-at-law myself you programmer folk keep harassing
      me with rabulistic nitpickings about free software licenses. I'm
      releasing morphic.js under an AGPL license. Therefore please make
      sure to adhere to that license in any minified or compressed version.
  
  
      VIII. acknowledgements
      ----------------------
      The original Morphic was designed and written by Randy Smith and
      John Maloney for the SELF programming language, and later ported to
      Squeak (Smalltalk) by John Maloney and Dan Ingalls, who has also
      ported it to JavaScript (the Lively Kernel), once again setting
      a "Gold Standard" for self sustaining systems which morphic.js
      cannot and does not aspire to meet.
  
      This Morphic implementation for JavaScript is not a direct port of
      Squeak's Morphic, but still many individual functions have been
      ported almost literally from Squeak, sometimes even including their
      comments, e.g. the morph duplication mechanism fullCopy(). Squeak
      has been a treasure trove, and if morphic.js looks, feels and
      smells a lot like Squeak, I'll take it as a compliment.
  
      Evelyn Eastmond has inspired and encouraged me with her wonderful
      implementation of DesignBlocksJS. Thanks for sharing code, ideas
      and enthusiasm for programming.
  
      John Maloney has been my mentor and my source of inspiration for
      these Morphic experiments. Thanks for the critique, the suggestions
      and explanations for all things Morphic and for being my all time
      programming hero.
  
      I have originally written morphic.js in Florian Balmer's Notepad2
      editor for Windows, later switched to Apple's Dashcode and later
      still to Apple's Xcode. I've also come to depend on both Douglas
      Crockford's JSLint and later the JSHint project, as well as on
      Mozilla's Firebug and Google's Chrome to get
      it right.
  
  
      IX. contributors
      ----------------------
      Joe Otto found and fixed many early bugs and taught me some tricks.
      Nathan Dinsmore contributed mouse wheel scrolling, cached
      background texture handling, countless bug fixes and optimizations.
      Ian Reynolds contributed backspace key handling for Chrome.
      Davide Della Casa contributed performance optimizations for Firefox.
      Jason N (@cyderize) contributed native copy & paste for text editing.
      Bartosz Leper contributed retina display support.
      Brian Harvey contributed to the design and implementation of submenus.
  
      - Jens Mönig
  */
  
  // Global settings /////////////////////////////////////////////////////
  
  /*global window, HTMLCanvasElement, FileReader, Audio, FileList*/
  
  var morphicVersion = '2018-January-04';
  var modules = {}; // keep track of additional loaded modules
  var useBlurredShadows = getBlurredShadowSupport(); // check for Chrome-bug
  
  var standardSettings = {
      minimumFontHeight: getMinimumFontHeight(), // browser settings
      globalFontFamily: '',
      menuFontName: 'sans-serif',
      menuFontSize: 12,
      bubbleHelpFontSize: 10,
      prompterFontName: 'sans-serif',
      prompterFontSize: 12,
      prompterSliderSize: 10,
      handleSize: 15,
      scrollBarSize: 12,
      mouseScrollAmount: 40,
      useSliderForInput: false,
      useVirtualKeyboard: true,
      isTouchDevice: false, // turned on by touch events, don't set
      rasterizeSVGs: false,
      isFlat: false,
      grabThreshold: 5
  };
  
  var touchScreenSettings = {
      minimumFontHeight: standardSettings.minimumFontHeight,
      globalFontFamily: '',
      menuFontName: 'sans-serif',
      menuFontSize: 24,
      bubbleHelpFontSize: 18,
      prompterFontName: 'sans-serif',
      prompterFontSize: 24,
      prompterSliderSize: 20,
      handleSize: 26,
      scrollBarSize: 24,
      mouseScrollAmount: 40,
      useSliderForInput: true,
      useVirtualKeyboard: true,
      isTouchDevice: false,
      rasterizeSVGs: false,
      isFlat: false,
      grabThreshold: 5
  };
  
  var MorphicPreferences = standardSettings;
  
  // first, try enabling support for retina displays - can be turned off later
  
  /*
      Support for retina displays has been pioneered and contributed by
      Bartosz Leper.
  
      NOTE: this will make changes to the HTMLCanvasElement that - mostly -
      make Morphic usable on retina displays in very high resolution mode
      with crisp fonts and clear fine lines without you (the programmer)
      needing to know any specifics, provided both the display and the browser
      support these (Safari currently doesn't), otherwise these utilities will
      not be installed.
      If you don't want your Morphic application to support retina resolutions
      you don't have to edit this morphic.js file to comment out the next line
      of code, instead you can simply call
  
          disableRetinaSupport();
  
      before you create your World(s) in the html page. Disabling retina
      support also will simply do nothing if retina support is not possible
      or already disabled, so it's equally safe to call.
  
      For an example how to make retina support user-specifiable refer to
      Snap! >> guis.js >> toggleRetina()
  */
  
  enableRetinaSupport();
  
  // Global Functions ////////////////////////////////////////////////////
  
  function nop() {
      // do explicitly nothing
      return null;
  }
  
  function localize(string) {
      // override this function with custom localizations
      return string;
  }
  
  function isNil(thing) {
      return thing === undefined || thing === null;
  }
  
  function contains(list, element) {
      // answer true if element is a member of list
      return list.indexOf(element) !== -1;
  }
  
  function detect(list, predicate) {
      // answer the first element of list for which predicate evaluates
      // true, otherwise answer null
      var i, size = list.length;
      for (i = 0; i < size; i += 1) {
          if (predicate.call(null, list[i])) {
              return list[i];
          }
      }
      return null;
  }
  
  function sizeOf(object) {
      // answer the number of own properties
      var size = 0, key;
      for (key in object) {
          if (Object.prototype.hasOwnProperty.call(object, key)) {
              size += 1;
          }
      }
      return size;
  }
  
  function isString(target) {
      return typeof target === 'string' || target instanceof String;
  }
  
  function isObject(target) {
      return target !== null &&
          (typeof target === 'object' || target instanceof Object);
  }
  
  function radians(degrees) {
      return degrees * Math.PI / 180;
  }
  
  function degrees(radians) {
      return radians * 180 / Math.PI;
  }
  
  function fontHeight(height) {
      var minHeight = Math.max(height, MorphicPreferences.minimumFontHeight);
      return minHeight * 1.2; // assuming 1/5 font size for ascenders
  }
  
  function isWordChar(aCharacter) {
      // can't use \b or \w because they ignore diacritics
      return aCharacter.match(/[A-zÀ-ÿ0-9]/);
  }
  
  function newCanvas(extentPoint, nonRetina) {
      // answer a new empty instance of Canvas, don't display anywhere
      // nonRetina - optional Boolean "false"
      // by default retina support is automatic
      var canvas, ext;
      ext = extentPoint || {x: 0, y: 0};
      canvas = document.createElement('canvas');
      canvas.width = ext.x;
      canvas.height = ext.y;
      if (nonRetina && canvas.isRetinaEnabled) {
          canvas.isRetinaEnabled = false;
      }
      return canvas;
  }
  
  function getMinimumFontHeight() {
      // answer the height of the smallest font renderable in pixels
      var str = 'I',
          size = 50,
          canvas = document.createElement('canvas'),
          ctx,
          maxX,
          data,
          x,
          y;
      canvas.width = size;
      canvas.height = size;
      ctx = canvas.getContext('2d');
      ctx.font = '1px serif';
      maxX = ctx.measureText(str).width;
      ctx.fillStyle = 'black';
      ctx.textBaseline = 'bottom';
      ctx.fillText(str, 0, size);
      for (y = 0; y < size; y += 1) {
          for (x = 0; x < maxX; x += 1) {
              data = ctx.getImageData(x, y, 1, 1);
              if (data.data[3] !== 0) {
                  return size - y + 1;
              }
          }
      }
      return 0;
  }
  
  function getBlurredShadowSupport() {
      // check for Chrome issue 90001
      // http://code.google.com/p/chromium/issues/detail?id=90001
      var source, target, ctx;
      source = document.createElement('canvas');
      source.width = 10;
      source.height = 10;
      ctx = source.getContext('2d');
      ctx.fillStyle = 'rgb(255, 0, 0)';
      ctx.beginPath();
      ctx.arc(5, 5, 5, 0, Math.PI * 2, true);
      ctx.closePath();
      ctx.fill();
      target = document.createElement('canvas');
      target.width = 10;
      target.height = 10;
      ctx = target.getContext('2d');
      ctx.shadowBlur = 10;
      ctx.shadowColor = 'rgba(0, 0, 255, 1)';
      ctx.drawImage(source, 0, 0);
      return ctx.getImageData(0, 0, 1, 1).data[3] ? true : false;
  }
  
  function getDocumentPositionOf(aDOMelement) {
      // answer the absolute coordinates of a DOM element in the document
      var pos, offsetParent;
      if (aDOMelement === null) {
          return {x: 0, y: 0};
      }
      pos = {x: aDOMelement.offsetLeft, y: aDOMelement.offsetTop};
      offsetParent = aDOMelement.offsetParent;
      while (offsetParent !== null) {
          pos.x += offsetParent.offsetLeft;
          pos.y += offsetParent.offsetTop;
          if (offsetParent !== document.body &&
                  offsetParent !== document.documentElement) {
              pos.x -= offsetParent.scrollLeft;
              pos.y -= offsetParent.scrollTop;
          }
          offsetParent = offsetParent.offsetParent;
      }
      return pos;
  }
  
  function copy(target) {
      // answer a shallow copy of target
      var value, c, property, keys, l, i;
  
      if (typeof target !== 'object') {
          return target;
      }
      value = target.valueOf();
      if (target !== value) {
          return new target.constructor(value);
      }
      if (target instanceof target.constructor &&
              target.constructor !== Object) {
          c = Object.create(target.constructor.prototype);
          keys = Object.keys(target);
          for (l = keys.length, i = 0; i < l; i += 1) {
              property = keys[i];
              c[property] = target[property];
          }
      } else {
          c = {};
          for (property in target) {
              c[property] = target[property];
          }
      }
      return c;
  }
  
  // Retina Display Support //////////////////////////////////////////////
  
  /*
      By default retina support gets installed when Morphic.js loads. There
      are two global functions that let you test for retina availability:
  
          isRetinaSupported() - Boolean, whether retina support is available
          isRetinaEnabled()   - Boolean, whether currently in retina mode
  
      and two more functions that let you control retina support if it is
      available:
  
          enableRetinaSupport()
          disableRetinaSupport()
  
      Both of these internally test whether retina is available, so they are
      safe to call directly.
  
      Even when in retina mode it often makes sense to use non-high-resolution
      canvasses for simple shapes in order to save system resources and
      optimize performance. Examples are costumes and backgrounds in Snap.
      In Morphic you can create new canvas elements using
      
          newCanvas(extentPoint [, nonRetinaFlag])
  
      If retina support is enabled such new canvasses will automatically be
      high-resolution canvasses, unless the newCanvas() function is given an
      otherwise optional second Boolean <true> argument that explicitly makes
      it a non-retina canvas.
  
      Not the whole canvas API is supported by Morphic's retina utilities.
      Especially if your code uses putImageData() you will want to "downgrade"
      a target high-resolution canvas to a normal-resolution ("non-retina")
      one before using
  
          normalizeCanvas(aCanvas [, copyFlag])
  
      This will change the target canvas' resolution in place (!). If you
      pass in the optional second Boolean <true> flag the function returns
      a non-retina copy and leaves the target canvas unchanged. An example
      of this normalize mechanism is converting the penTrails layer of Snap's
      stage (high-resolution) into a sprite-costume (normal resolution).
  */
  
  function enableRetinaSupport() {
  /*
      === contributed by Bartosz Leper ===
  
      This installs a series of utilities that allow using Canvas the same way
      on retina and non-retina displays. If the display is a retina one, the
      underlying dimensions of the Canvas elements are doubled, but this will
      be transparent to the code that uses Canvas. All dimensions read or
      written to the Canvas element will be scaled appropriately.
  
      NOTE: This implementation is not exhaustive; it only implements what is
      needed by the Snap! UI.
      
      [Jens]: like all other retina screen support implementations I've seen
      Bartosz's patch also does not address putImageData() compatibility when
      mixing retina-enabled and non-retina canvasses. If you need to manipulate
      pixels in such mixed canvasses, make sure to "downgrade" them all using
      normalizeCanvas() below.
  */
  
      // Get the window's pixel ratio for canvas elements.
      // See: http://www.html5rocks.com/en/tutorials/canvas/hidpi/
      var ctx = document.createElement("canvas").getContext("2d"),
          backingStorePixelRatio = ctx.webkitBackingStorePixelRatio ||
              ctx.mozBackingStorePixelRatio ||
              ctx.msBackingStorePixelRatio ||
              ctx.oBackingStorePixelRatio ||
              ctx.backingStorePixelRatio || 1,
  
      // Unfortunately, it's really hard to make this work well when changing
      // zoom level, so let's leave it like this right now, and stick to
      // whatever the ratio was in the beginning.
  
          // originalDevicePixelRatio = window.devicePixelRatio,
  
      // [Jens]: As of summer 2016 non-integer devicePixelRatios lead to
      // artifacts when blitting images onto canvas elements in all browsers
      // except Chrome, especially Firefox, Edge, IE (Safari doesn't even
      // support retina mode as implemented here).
      // therefore - to ensure crisp fonts - use the ceiling of whatever
      // the devicePixelRatio is. This needs more memory, but looks nicer.
  
          originalDevicePixelRatio = Math.ceil(window.devicePixelRatio),
  
          canvasProto = HTMLCanvasElement.prototype,
          contextProto = CanvasRenderingContext2D.prototype,
  
      // [Jens]: keep track of original properties in a dictionary
      // so they can be iterated over and restored
          uber = {
              drawImage: contextProto.drawImage,
              getImageData: contextProto.getImageData,
  
              width: Object.getOwnPropertyDescriptor(
                  canvasProto,
                  'width'
              ),
              height: Object.getOwnPropertyDescriptor(
                  canvasProto,
                  'height'
              ),
              shadowOffsetX: Object.getOwnPropertyDescriptor(
                  contextProto,
                  'shadowOffsetX'
              ),
              shadowOffsetY: Object.getOwnPropertyDescriptor(
                  contextProto,
                  'shadowOffsetY'
              ),
              shadowBlur: Object.getOwnPropertyDescriptor(
                  contextProto,
                  'shadowBlur'
              )
          };
  
      // [Jens]: only install retina utilities if the display supports them
      if (backingStorePixelRatio === originalDevicePixelRatio) {return; }
      // [Jens]: check whether properties can be overridden, needed for Safari
      if (Object.keys(uber).some(function (any) {
          var prop = uber[any];
          return prop.hasOwnProperty('configurable') && (!prop.configurable);
      })) {return; }
  
      function getPixelRatio(imageSource) {
          return imageSource.isRetinaEnabled ?
              (originalDevicePixelRatio || 1) / backingStorePixelRatio : 1;
      }
  
      canvasProto._isRetinaEnabled = true;
      // [Jens]: remember the original non-retina properties,
      // so they can be restored again
      canvasProto._bak = uber;
  
      Object.defineProperty(canvasProto, 'isRetinaEnabled', {
          get: function() {
              return this._isRetinaEnabled;
          },
          set: function(enabled) {
              var prevPixelRatio = getPixelRatio(this),
                  prevWidth = this.width,
                  prevHeight = this.height;
  
              this._isRetinaEnabled = enabled;
              if (getPixelRatio(this) != prevPixelRatio) {
                  this.width = prevWidth;
                  this.height = prevHeight;
              }
          },
          configurable: true // [Jens]: allow to be deleted an reconfigured
      });
  
      Object.defineProperty(canvasProto, 'width', {
          get: function() {
              return uber.width.get.call(this) / getPixelRatio(this);
          },
          set: function(width) {
              try { // workaround one of FF's dreaded NS_ERROR_FAILURE bugs
                  // this should be taken out as soon as FF gets fixed again
                  var pixelRatio = getPixelRatio(this),
                      context;
                  uber.width.set.call(this, width * pixelRatio);
                  context = this.getContext('2d');
                  context.restore();
                  context.save();
                  context.scale(pixelRatio, pixelRatio);
              } catch (err) {
                  console.log('Retina Display Support Problem', err);
                  uber.width.set.call(this, width);
              }
          }
      });
  
      Object.defineProperty(canvasProto, 'height', {
          get: function() {
              return uber.height.get.call(this) / getPixelRatio(this);
          },
          set: function(height) {
              var pixelRatio = getPixelRatio(this),
                  context;
              uber.height.set.call(this, height * pixelRatio);
              context = this.getContext('2d');
              context.restore();
              context.save();
              context.scale(pixelRatio, pixelRatio);
          }
      });
  
      contextProto.drawImage = function(image) {
          var pixelRatio = getPixelRatio(image),
              sx, sy, sWidth, sHeight, dx, dy, dWidth, dHeight;
          
          // Different signatures of drawImage() method have different
          // parameter assignments.
          switch (arguments.length) {
              case 9:
                  sx = arguments[1];
                  sy = arguments[2];
                  sWidth = arguments[3];
                  sHeight = arguments[4];
                  dx = arguments[5];
                  dy = arguments[6];
                  dWidth = arguments[7];
                  dHeight = arguments[8];
                  break;
  
              case 5:
                  sx = 0;
                  sy = 0;
                  sWidth = image.width;
                  sHeight = image.height;
                  dx = arguments[1];
                  dy = arguments[2];
                  dWidth = arguments[3];
                  dHeight = arguments[4];
                  break;
  
              case 3:
                  sx = 0;
                  sy = 0;
                  sWidth = image.width;
                  sHeight = image.height;
                  dx = arguments[1];
                  dy = arguments[2];
                  dWidth = image.width;
                  dHeight = image.height;
                  break;
  
              default:
                  throw Error('Called drawImage() with ' + arguments.length +
                          ' arguments');
          }
          uber.drawImage.call(
                  this, image,
                  sx * pixelRatio, sy * pixelRatio,
                  sWidth * pixelRatio, sHeight * pixelRatio,
                  dx, dy,
                  dWidth, dHeight);
      };
  
      contextProto.getImageData = function(sx, sy, sw, sh) {
          var pixelRatio = getPixelRatio(this.canvas);
          return uber.getImageData.call(
                  this,
                  sx * pixelRatio, sy * pixelRatio,
                  sw * pixelRatio, sh * pixelRatio);
      };
  
      Object.defineProperty(contextProto, 'shadowOffsetX', {
          get: function() {
              return uber.shadowOffsetX.get.call(this) /
                  getPixelRatio(this.canvas);
          },
          set: function(offset) {
              var pixelRatio = getPixelRatio(this.canvas);
              uber.shadowOffsetX.set.call(this, offset * pixelRatio);
          }
      });
  
      Object.defineProperty(contextProto, 'shadowOffsetY', {
          get: function() {
              return uber.shadowOffsetY.get.call(this) /
                  getPixelRatio(this.canvas);
          },
          set: function(offset) {
              var pixelRatio = getPixelRatio(this.canvas);
              uber.shadowOffsetY.set.call(this, offset * pixelRatio);
          }
      });
  
      Object.defineProperty(contextProto, 'shadowBlur', {
          get: function() {
              return uber.shadowBlur.get.call(this) /
                  getPixelRatio(this.canvas);
          },
          set: function(blur) {
              var pixelRatio = getPixelRatio(this.canvas);
              uber.shadowBlur.set.call(this, blur * pixelRatio);
          }
      });
  }
  
  function isRetinaSupported () {
      var ctx = document.createElement("canvas").getContext("2d"),
          backingStorePixelRatio = ctx.webkitBackingStorePixelRatio ||
              ctx.mozBackingStorePixelRatio ||
              ctx.msBackingStorePixelRatio ||
              ctx.oBackingStorePixelRatio ||
              ctx.backingStorePixelRatio || 1,
          canvasProto = HTMLCanvasElement.prototype,
          contextProto = CanvasRenderingContext2D.prototype,
          uber = {
              drawImage: contextProto.drawImage,
              getImageData: contextProto.getImageData,
  
              width: Object.getOwnPropertyDescriptor(
                  canvasProto,
                  'width'
              ),
              height: Object.getOwnPropertyDescriptor(
                  canvasProto,
                  'height'
              ),
              shadowOffsetX: Object.getOwnPropertyDescriptor(
                  contextProto,
                  'shadowOffsetX'
              ),
              shadowOffsetY: Object.getOwnPropertyDescriptor(
                  contextProto,
                  'shadowOffsetY'
              ),
              shadowBlur: Object.getOwnPropertyDescriptor(
                  contextProto,
                  'shadowBlur'
              )
          };
      return backingStorePixelRatio !== window.devicePixelRatio &&
          !(Object.keys(uber).some(function (any) {
              var prop = uber[any];
              return prop.hasOwnProperty('configurable') && (!prop.configurable);
          })
      );
  }
  
  function isRetinaEnabled () {
      return HTMLCanvasElement.prototype.hasOwnProperty('_isRetinaEnabled');
  }
  
  function disableRetinaSupport() {
      // uninstalls Retina utilities. Make sure to re-create every Canvas
      // element afterwards
      var canvasProto, contextProto, uber;
      if (!isRetinaEnabled()) {return; }
      canvasProto = HTMLCanvasElement.prototype;
      contextProto = CanvasRenderingContext2D.prototype;
      uber = canvasProto._bak;
      Object.defineProperty(canvasProto, 'width', uber.width);
      Object.defineProperty(canvasProto, 'height', uber.height);
      contextProto.drawImage = uber.drawImage;
      contextProto.getImageData = uber.getImageData;
      Object.defineProperty(contextProto, 'shadowOffsetX', uber.shadowOffsetX);
      Object.defineProperty(contextProto, 'shadowOffsetY', uber.shadowOffsetY);
      Object.defineProperty(contextProto, 'shadowBlur', uber.shadowBlur);
      delete canvasProto._isRetinaEnabled;
      delete canvasProto.isRetinaEnabled;
      delete canvasProto._bak;
  }
  
  function normalizeCanvas(aCanvas, getCopy) {
      // make sure aCanvas is non-retina, otherwise convert it in place (!)
      // or answer a normalized copy if the "getCopy" flag is <true>
      var cpy;
      if (!aCanvas.isRetinaEnabled) {return aCanvas; }
      cpy = newCanvas(new Point(aCanvas.width, aCanvas.height), true);
      cpy.getContext('2d').drawImage(aCanvas, 0, 0);
      if (getCopy) {return cpy; }
      aCanvas.isRetinaEnabled = false;
      aCanvas.width = cpy.width;
      aCanvas.height = cpy.height;
      aCanvas.getContext('2d').drawImage(cpy, 0, 0);
      return aCanvas;
  }
  
  // Animations //////////////////////////////////////////////////////////////
  
  /*
      Animations handle gradual transitions between one state and another over a
      period of time. Transition effects can be specified using easing functions.
      An easing function maps a fraction of the transition time to a fraction of
      the state delta. This way accelerating / decelerating and bouncing sliding
      effects can be accomplished.
  
      Animations are generic and not limited to motion, i.e. they can also handle
      other transitions such as color changes, transparency fadings, growing,
      shrinking, turning etc.
  
      Animations need to be stepped by a scheduler, e. g. an interval function.
      In Morphic the preferred way to run an animation is to register it with
      the World by adding it to the World's animation queue. The World steps each
      registered animation once per display cycle independently of the Morphic
      stepping mechanism.
  
      For an example how to use animations look at how the Morph's methods
      
          glideTo()
          fadeTo()
  
      and
      
          slideBackTo()
  
      are implemented.
  */
  
  // Animation instance creation:
  
  function Animation(setter, getter, delta, duration, easing, onComplete) {
      this.setter = setter; // function
      this.getter = getter; // function
      this.delta = delta || 0; // number
      this.duration = duration || 0; // milliseconds
      this.easing = isString(easing) ? // string or function
              this.easings[easing] || this.easings.sinusoidal
                  : easing || this.easings.sinusoidal;
      this.onComplete = onComplete || null; // optional callback
      this.endTime = null;
      this.destination = null;
      this.isActive = false;
      this.start();
  }
  
  Animation.prototype.easings = {
      // dictionary of a few pre-defined easing functions used to transition
      // two states
  
      // ease both in and out:
      linear: function (t) {return t; },
      sinusoidal: function (t) {return 1 - Math.cos(radians(t * 90)); },
      quadratic: function (t) {
          return t < 0.5 ?
                  2 * t * t
                      : ((4 - (2 * t)) * t) - 1;
      },
      cubic: function (t) {
          return t < 0.5 ?
                  4 * t * t * t
                      : ((t - 1) * ((2 * t) - 2) * ((2 * t) - 2)) + 1;
      },
      elastic: function (t) {
          return (t -= 0.5) < 0 ?
              (0.01 + 0.01 / t) * Math.sin(50 * t)
                  : (0.02 - 0.01 / t) * Math.sin(50 * t) + 1;
      },
  
      // ease in only:
      sine_in: function (t) {return 1 - Math.sin(radians(90 + (t * 90))); },
      quad_in: function (t) {return t * t; },
      cubic_in: function (t) {return t * t * t; },
      elastic_in: function (t) {
          return (0.04 - 0.04 / t) * Math.sin(25 * t) + 1;
      },
  
      // ease out only:
      sine_out: function (t) {return Math.sin(radians(t * 90)); },
      quad_out: function (t) {return t * (2 - t); },
      elastic_out: function (t) {return 0.04 * t / (--t) * Math.sin(25 * t); }
  };
  
  Animation.prototype.start = function () {
      // (re-) activate the animation, e.g. if is has previously completed,
      // make sure to plug it into something that repeatedly triggers step(),
      // e.g. the World's animations queue
      this.endTime = Date.now() + this.duration;
      this.destination = this.getter.call(this) + this.delta;
      this.isActive = true;
  };
  
  Animation.prototype.step = function () {
      if (!this.isActive) {return; }
      var now = Date.now();
      if (now > this.endTime) {
          this.setter(this.destination);
          this.isActive = false;
          if (this.onComplete) {this.onComplete(); }
      } else {
          this.setter(
              this.destination -
                  (this.delta * this.easing((this.endTime - now) / this.duration))
          );
      }
  };
  
  // Colors //////////////////////////////////////////////////////////////
  
  // Color instance creation:
  
  function Color(r, g, b, a) {
      // all values are optional, just (r, g, b) is fine
      this.r = r || 0;
      this.g = g || 0;
      this.b = b || 0;
      this.a = a || ((a === 0) ? 0 : 1);
  }
  
  // Color string representation: e.g. 'rgba(255,165,0,1)'
  
  Color.prototype.toString = function () {
      return 'rgba(' +
          Math.round(this.r) + ',' +
          Math.round(this.g) + ',' +
          Math.round(this.b) + ',' +
          this.a + ')';
  };
  
  // Color copying:
  
  Color.prototype.copy = function () {
      return new Color(
          this.r,
          this.g,
          this.b,
          this.a
      );
  };
  
  // Color comparison:
  
  Color.prototype.eq = function (aColor) {
      // ==
      return aColor &&
          this.r === aColor.r &&
          this.g === aColor.g &&
          this.b === aColor.b;
  };
  
  // Color conversion (hsv):
  
  Color.prototype.hsv = function () {
      // ignore alpha
      var max, min, h, s, v, d,
          rr = this.r / 255,
          gg = this.g / 255,
          bb = this.b / 255;
      max = Math.max(rr, gg, bb);
      min = Math.min(rr, gg, bb);
      h = max;
      s = max;
      v = max;
      d = max - min;
      s = max === 0 ? 0 : d / max;
      if (max === min) {
          h = 0;
      } else {
          switch (max) {
          case rr:
              h = (gg - bb) / d + (gg < bb ? 6 : 0);
              break;
          case gg:
              h = (bb - rr) / d + 2;
              break;
          case bb:
              h = (rr - gg) / d + 4;
              break;
          }
          h /= 6;
      }
      return [h, s, v];
  };
  
  Color.prototype.set_hsv = function (h, s, v) {
      // ignore alpha, h, s and v are to be within [0, 1]
      var i, f, p, q, t;
      i = Math.floor(h * 6);
      f = h * 6 - i;
      p = v * (1 - s);
      q = v * (1 - f * s);
      t = v * (1 - (1 - f) * s);
      switch (i % 6) {
      case 0:
          this.r = v;
          this.g = t;
          this.b = p;
          break;
      case 1:
          this.r = q;
          this.g = v;
          this.b = p;
          break;
      case 2:
          this.r = p;
          this.g = v;
          this.b = t;
          break;
      case 3:
          this.r = p;
          this.g = q;
          this.b = v;
          break;
      case 4:
          this.r = t;
          this.g = p;
          this.b = v;
          break;
      case 5:
          this.r = v;
          this.g = p;
          this.b = q;
          break;
      }
  
      this.r *= 255;
      this.g *= 255;
      this.b *= 255;
  
  };
  
  // Color mixing:
  
  Color.prototype.mixed = function (proportion, otherColor) {
      // answer a copy of this color mixed with another color, ignore alpha
      var frac1 = Math.min(Math.max(proportion, 0), 1),
          frac2 = 1 - frac1;
      return new Color(
          this.r * frac1 + otherColor.r * frac2,
          this.g * frac1 + otherColor.g * frac2,
          this.b * frac1 + otherColor.b * frac2
      );
  };
  
  Color.prototype.darker = function (percent) {
      // return an rgb-interpolated darker copy of me, ignore alpha
      var fract = 0.8333;
      if (percent) {
          fract = (100 - percent) / 100;
      }
      return this.mixed(fract, new Color(0, 0, 0));
  };
  
  Color.prototype.lighter = function (percent) {
      // return an rgb-interpolated lighter copy of me, ignore alpha
      var fract = 0.8333;
      if (percent) {
          fract = (100 - percent) / 100;
      }
      return this.mixed(fract, new Color(255, 255, 255));
  };
  
  Color.prototype.dansDarker = function () {
      // return an hsv-interpolated darker copy of me, ignore alpha
      var hsv = this.hsv(),
          result = new Color(),
          vv = Math.max(hsv[2] - 0.16, 0);
      result.set_hsv(hsv[0], hsv[1], vv);
      return result;
  };
  
  Color.prototype.inverted = function () {
      return new Color(
          255 - this.r,
          255 - this.g,
          255 - this.b
      );
  };
  
  // Points //////////////////////////////////////////////////////////////
  
  // Point instance creation:
  
  function Point(x, y) {
      this.x = x || 0;
      this.y = y || 0;
  }
  
  // Point string representation: e.g. '12@68'
  
  Point.prototype.toString = function () {
      return Math.round(this.x.toString()) +
          '@' + Math.round(this.y.toString());
  };
  
  // Point copying:
  
  Point.prototype.copy = function () {
      return new Point(this.x, this.y);
  };
  
  // Point comparison:
  
  Point.prototype.eq = function (aPoint) {
      // ==
      return this.x === aPoint.x && this.y === aPoint.y;
  };
  
  Point.prototype.lt = function (aPoint) {
      // <
      return this.x < aPoint.x && this.y < aPoint.y;
  };
  
  Point.prototype.gt = function (aPoint) {
      // >
      return this.x > aPoint.x && this.y > aPoint.y;
  };
  
  Point.prototype.ge = function (aPoint) {
      // >=
      return this.x >= aPoint.x && this.y >= aPoint.y;
  };
  
  Point.prototype.le = function (aPoint) {
      // <=
      return this.x <= aPoint.x && this.y <= aPoint.y;
  };
  
  Point.prototype.max = function (aPoint) {
      return new Point(Math.max(this.x, aPoint.x),
          Math.max(this.y, aPoint.y));
  };
  
  Point.prototype.min = function (aPoint) {
      return new Point(Math.min(this.x, aPoint.x),
          Math.min(this.y, aPoint.y));
  };
  
  // Point conversion:
  
  Point.prototype.round = function () {
      return new Point(Math.round(this.x), Math.round(this.y));
  };
  
  Point.prototype.abs = function () {
      return new Point(Math.abs(this.x), Math.abs(this.y));
  };
  
  Point.prototype.neg = function () {
      return new Point(-this.x, -this.y);
  };
  
  Point.prototype.mirror = function () {
      return new Point(this.y, this.x);
  };
  
  Point.prototype.floor = function () {
      return new Point(
          Math.max(Math.floor(this.x), 0),
          Math.max(Math.floor(this.y), 0)
      );
  };
  
  Point.prototype.ceil = function () {
      return new Point(Math.ceil(this.x), Math.ceil(this.y));
  };
  
  // Point arithmetic:
  
  Point.prototype.add = function (other) {
      if (other instanceof Point) {
          return new Point(this.x + other.x, this.y + other.y);
      }
      return new Point(this.x + other, this.y + other);
  };
  
  Point.prototype.subtract = function (other) {
      if (other instanceof Point) {
          return new Point(this.x - other.x, this.y - other.y);
      }
      return new Point(this.x - other, this.y - other);
  };
  
  Point.prototype.multiplyBy = function (other) {
      if (other instanceof Point) {
          return new Point(this.x * other.x, this.y * other.y);
      }
      return new Point(this.x * other, this.y * other);
  };
  
  Point.prototype.divideBy = function (other) {
      if (other instanceof Point) {
          return new Point(this.x / other.x, this.y / other.y);
      }
      return new Point(this.x / other, this.y / other);
  };
  
  Point.prototype.floorDivideBy = function (other) {
      if (other instanceof Point) {
          return new Point(Math.floor(this.x / other.x),
              Math.floor(this.y / other.y));
      }
      return new Point(Math.floor(this.x / other),
          Math.floor(this.y / other));
  };
  
  // Point polar coordinates:
  
  Point.prototype.r = function () {
      var t = (this.multiplyBy(this));
      return Math.sqrt(t.x + t.y);
  };
  
  Point.prototype.degrees = function () {
  /*
      answer the angle I make with origin in degrees.
      Right is 0, down is 90
  */
      var tan, theta;
  
      if (this.x === 0) {
          if (this.y >= 0) {
              return 90;
          }
          return 270;
      }
      tan = this.y / this.x;
      theta = Math.atan(tan);
      if (this.x >= 0) {
          if (this.y >= 0) {
              return degrees(theta);
          }
          return 360 + (degrees(theta));
      }
      return 180 + degrees(theta);
  };
  
  Point.prototype.theta = function () {
  /*
      answer the angle I make with origin in radians.
      Right is 0, down is 90
  */
      var tan, theta;
  
      if (this.x === 0) {
          if (this.y >= 0) {
              return radians(90);
          }
          return radians(270);
      }
      tan = this.y / this.x;
      theta = Math.atan(tan);
      if (this.x >= 0) {
          if (this.y >= 0) {
              return theta;
          }
          return radians(360) + theta;
      }
      return radians(180) + theta;
  };
  
  // Point functions:
  
  Point.prototype.crossProduct = function (aPoint) {
      return this.multiplyBy(aPoint.mirror());
  };
  
  Point.prototype.distanceTo = function (aPoint) {
      return (aPoint.subtract(this)).r();
  };
  
  Point.prototype.rotate = function (direction, center) {
      // direction must be 'right', 'left' or 'pi'
      var offset = this.subtract(center);
      if (direction === 'right') {
          return new Point(-offset.y, offset.y).add(center);
      }
      if (direction === 'left') {
          return new Point(offset.y, -offset.y).add(center);
      }
      // direction === 'pi'
      return center.subtract(offset);
  };
  
  Point.prototype.flip = function (direction, center) {
      // direction must be 'vertical' or 'horizontal'
      if (direction === 'vertical') {
          return new Point(this.x, center.y * 2 - this.y);
      }
      // direction === 'horizontal'
      return new Point(center.x * 2 - this.x, this.y);
  };
  
  Point.prototype.distanceAngle = function (dist, angle) {
      var deg = angle, x, y;
      if (deg > 270) {
          deg = deg - 360;
      } else if (deg < -270) {
          deg = deg + 360;
      }
      if (-90 <= deg && deg <= 90) {
          x = Math.sin(radians(deg)) * dist;
          y = Math.sqrt((dist * dist) - (x * x));
          return new Point(x + this.x, this.y - y);
      }
      x = Math.sin(radians(180 - deg)) * dist;
      y = Math.sqrt((dist * dist) - (x * x));
      return new Point(x + this.x, this.y + y);
  };
  
  // Point transforming:
  
  Point.prototype.scaleBy = function (scalePoint) {
      return this.multiplyBy(scalePoint);
  };
  
  Point.prototype.translateBy = function (deltaPoint) {
      return this.add(deltaPoint);
  };
  
  Point.prototype.rotateBy = function (angle, centerPoint) {
      var center = centerPoint || new Point(0, 0),
          p = this.subtract(center),
          r = p.r(),
          theta = angle - p.theta();
      return new Point(
          center.x + (r * Math.cos(theta)),
          center.y - (r * Math.sin(theta))
      );
  };
  
  // Point conversion:
  
  Point.prototype.asArray = function () {
      return [this.x, this.y];
  };
  
  // Rectangles //////////////////////////////////////////////////////////
  
  // Rectangle instance creation:
  
  function Rectangle(left, top, right, bottom) {
      this.init(new Point((left || 0), (top || 0)),
              new Point((right || 0), (bottom || 0)));
  }
  
  Rectangle.prototype.init = function (originPoint, cornerPoint) {
      this.origin = originPoint;
      this.corner = cornerPoint;
  };
  
  // Rectangle string representation: e.g. '[0@0 | 160@80]'
  
  Rectangle.prototype.toString = function () {
      return '[' + this.origin.toString() + ' | ' +
          this.extent().toString() + ']';
  };
  
  // Rectangle copying:
  
  Rectangle.prototype.copy = function () {
      return new Rectangle(
          this.left(),
          this.top(),
          this.right(),
          this.bottom()
      );
  };
  
  // creating Rectangle instances from Points:
  
  Point.prototype.corner = function (cornerPoint) {
      // answer a new Rectangle
      return new Rectangle(
          this.x,
          this.y,
          cornerPoint.x,
          cornerPoint.y
      );
  };
  
  Point.prototype.rectangle = function (aPoint) {
      // answer a new Rectangle
      var org, crn;
      org = this.min(aPoint);
      crn = this.max(aPoint);
      return new Rectangle(org.x, org.y, crn.x, crn.y);
  };
  
  Point.prototype.extent = function (aPoint) {
      //answer a new Rectangle
      var crn = this.add(aPoint);
      return new Rectangle(this.x, this.y, crn.x, crn.y);
  };
  
  // Rectangle accessing - setting:
  
  Rectangle.prototype.setTo = function (left, top, right, bottom) {
      // note: all inputs are optional and can be omitted
  
      this.origin = new Point(
          left || ((left === 0) ? 0 : this.left()),
          top || ((top === 0) ? 0 : this.top())
      );
  
      this.corner = new Point(
          right || ((right === 0) ? 0 : this.right()),
          bottom || ((bottom === 0) ? 0 : this.bottom())
      );
  };
  
  // Rectangle accessing - getting:
  
  Rectangle.prototype.area = function () {
      //requires width() and height() to be defined
      var w = this.width();
      if (w < 0) {
          return 0;
      }
      return Math.max(w * this.height(), 0);
  };
  
  Rectangle.prototype.bottom = function () {
      return this.corner.y;
  };
  
  Rectangle.prototype.bottomCenter = function () {
      return new Point(this.center().x, this.bottom());
  };
  
  Rectangle.prototype.bottomLeft = function () {
      return new Point(this.origin.x, this.corner.y);
  };
  
  Rectangle.prototype.bottomRight = function () {
      return this.corner.copy();
  };
  
  Rectangle.prototype.boundingBox = function () {
      return this;
  };
  
  Rectangle.prototype.center = function () {
      return this.origin.add(
          this.corner.subtract(this.origin).floorDivideBy(2)
      );
  };
  
  Rectangle.prototype.corners = function () {
      return [this.origin,
          this.bottomLeft(),
          this.corner,
          this.topRight()];
  };
  
  Rectangle.prototype.extent = function () {
      return this.corner.subtract(this.origin);
  };
  
  Rectangle.prototype.height = function () {
      return this.corner.y - this.origin.y;
  };
  
  Rectangle.prototype.left = function () {
      return this.origin.x;
  };
  
  Rectangle.prototype.leftCenter = function () {
      return new Point(this.left(), this.center().y);
  };
  
  Rectangle.prototype.right = function () {
      return this.corner.x;
  };
  
  Rectangle.prototype.rightCenter = function () {
      return new Point(this.right(), this.center().y);
  };
  
  Rectangle.prototype.top = function () {
      return this.origin.y;
  };
  
  Rectangle.prototype.topCenter = function () {
      return new Point(this.center().x, this.top());
  };
  
  Rectangle.prototype.topLeft = function () {
      return this.origin;
  };
  
  Rectangle.prototype.topRight = function () {
      return new Point(this.corner.x, this.origin.y);
  };
  
  Rectangle.prototype.width = function () {
      return this.corner.x - this.origin.x;
  };
  
  Rectangle.prototype.position = function () {
      return this.origin;
  };
  
  // Rectangle comparison:
  
  Rectangle.prototype.eq = function (aRect) {
      return this.origin.eq(aRect.origin) &&
          this.corner.eq(aRect.corner);
  };
  
  Rectangle.prototype.abs = function () {
      var newOrigin, newCorner;
  
      newOrigin = this.origin.abs();
      newCorner = this.corner.max(newOrigin);
      return newOrigin.corner(newCorner);
  };
  
  // Rectangle functions:
  
  Rectangle.prototype.insetBy = function (delta) {
      // delta can be either a Point or a Number
      var result = new Rectangle();
      result.origin = this.origin.add(delta);
      result.corner = this.corner.subtract(delta);
      return result;
  };
  
  Rectangle.prototype.expandBy = function (delta) {
      // delta can be either a Point or a Number
      var result = new Rectangle();
      result.origin = this.origin.subtract(delta);
      result.corner = this.corner.add(delta);
      return result;
  };
  
  Rectangle.prototype.growBy = function (delta) {
      // delta can be either a Point or a Number
      var result = new Rectangle();
      result.origin = this.origin.copy();
      result.corner = this.corner.add(delta);
      return result;
  };
  
  Rectangle.prototype.intersect = function (aRect) {
      var result = new Rectangle();
      result.origin = this.origin.max(aRect.origin);
      result.corner = this.corner.min(aRect.corner);
      return result;
  };
  
  Rectangle.prototype.merge = function (aRect) {
      var result = new Rectangle();
      result.origin = this.origin.min(aRect.origin);
      result.corner = this.corner.max(aRect.corner);
      return result;
  };
  
  Rectangle.prototype.mergeWith = function (aRect) {
      // mutates myself
      this.origin = this.origin.min(aRect.origin);
      this.corner = this.corner.max(aRect.corner);
  };
  
  Rectangle.prototype.round = function () {
      return this.origin.round().corner(this.corner.round());
  };
  
  Rectangle.prototype.spread = function () {
      // round me by applying floor() to my origin and ceil() to my corner
      // expand by 1 to be on the safe side, this eliminates rounding
      // artifacts caused by Safari's auto-scaling on retina displays
      return this.origin.floor().corner(this.corner.ceil()).expandBy(1);
  };
  
  Rectangle.prototype.amountToTranslateWithin = function (aRect) {
  /*
      Answer a Point, delta, such that self + delta is forced within
      aRectangle. when all of me cannot be made to fit, prefer to keep
      my topLeft inside. Taken from Squeak.
  */
      var dx = 0, dy = 0;
  
      if (this.right() > aRect.right()) {
          dx = aRect.right() - this.right();
      }
      if (this.bottom() > aRect.bottom()) {
          dy = aRect.bottom() - this.bottom();
      }
      if ((this.left() + dx) < aRect.left()) {
          dx = aRect.left() - this.left();
      }
      if ((this.top() + dy) < aRect.top()) {
          dy = aRect.top() - this.top();
      }
      return new Point(dx, dy);
  };
  
  // Rectangle testing:
  
  Rectangle.prototype.containsPoint = function (aPoint) {
      return this.origin.le(aPoint) && aPoint.lt(this.corner);
  };
  
  Rectangle.prototype.containsRectangle = function (aRect) {
      return aRect.origin.gt(this.origin) &&
          aRect.corner.lt(this.corner);
  };
  
  Rectangle.prototype.intersects = function (aRect) {
      var ro = aRect.origin, rc = aRect.corner;
      return (rc.x >= this.origin.x) &&
          (rc.y >= this.origin.y) &&
          (ro.x <= this.corner.x) &&
          (ro.y <= this.corner.y);
  };
  
  Rectangle.prototype.isNearTo = function (aRect, threshold) {
      var ro = aRect.origin, rc = aRect.corner, border = threshold || 0;
      return (rc.x + border >= this.origin.x) &&
          (rc.y  + border >= this.origin.y) &&
          (ro.x - border <= this.corner.x) &&
          (ro.y - border <= this.corner.y);
  };
  
  // Rectangle transforming:
  
  Rectangle.prototype.scaleBy = function (scale) {
      // scale can be either a Point or a scalar
      var o = this.origin.multiplyBy(scale),
          c = this.corner.multiplyBy(scale);
      return new Rectangle(o.x, o.y, c.x, c.y);
  };
  
  Rectangle.prototype.translateBy = function (factor) {
      // factor can be either a Point or a scalar
      var o = this.origin.add(factor),
          c = this.corner.add(factor);
      return new Rectangle(o.x, o.y, c.x, c.y);
  };
  
  // Rectangle converting:
  
  Rectangle.prototype.asArray = function () {
      return [this.left(), this.top(), this.right(), this.bottom()];
  };
  
  Rectangle.prototype.asArray_xywh = function () {
      return [this.left(), this.top(), this.width(), this.height()];
  };
  
  // Nodes ///////////////////////////////////////////////////////////////
  
  // Node instance creation:
  
  function Node(parent, childrenArray) {
      this.init(parent || null, childrenArray || []);
  }
  
  Node.prototype.init = function (parent, childrenArray) {
      this.parent = parent || null;
      this.children = childrenArray || [];
  };
  
  // Node string representation: e.g. 'a Node[3]'
  
  Node.prototype.toString = function () {
      return 'a Node' + '[' + this.children.length.toString() + ']';
  };
  
  // Node accessing:
  
  Node.prototype.addChild = function (aNode) {
      this.children.push(aNode);
      aNode.parent = this;
  };
  
  Node.prototype.addChildFirst = function (aNode) {
      this.children.splice(0, null, aNode);
      aNode.parent = this;
  };
  
  Node.prototype.removeChild = function (aNode) {
      var idx = this.children.indexOf(aNode);
      if (idx !== -1) {
          this.children.splice(idx, 1);
      }
  };
  
  // Node functions:
  
  Node.prototype.root = function () {
      if (this.parent === null) {
          return this;
      }
      return this.parent.root();
  };
  
  Node.prototype.depth = function () {
      if (this.parent === null) {
          return 0;
      }
      return this.parent.depth() + 1;
  };
  
  Node.prototype.allChildren = function () {
      // includes myself
      var result = [this];
      this.children.forEach(function (child) {
          result = result.concat(child.allChildren());
      });
      return result;
  };
  
  Node.prototype.forAllChildren = function (aFunction) {
      if (this.children.length > 0) {
          this.children.forEach(function (child) {
              child.forAllChildren(aFunction);
          });
      }
      aFunction.call(null, this);
  };
  
  Node.prototype.anyChild = function (aPredicate) {
      // includes myself
      var i;
      if (aPredicate.call(null, this)) {
          return true;
      }
      for (i = 0; i < this.children.length; i += 1) {
          if (this.children[i].anyChild(aPredicate)) {
              return true;
          }
      }
      return false;
  };
  
  Node.prototype.allLeafs = function () {
      var result = [];
      this.allChildren().forEach(function (element) {
          if (element.children.length === 0) {
              result.push(element);
          }
      });
      return result;
  };
  
  Node.prototype.allParents = function () {
      // includes myself
      var result = [this];
      if (this.parent !== null) {
          result = result.concat(this.parent.allParents());
      }
      return result;
  };
  
  Node.prototype.siblings = function () {
      var myself = this;
      if (this.parent === null) {
          return [];
      }
      return this.parent.children.filter(function (child) {
          return child !== myself;
      });
  };
  
  Node.prototype.parentThatIsA = function (constructor) {
      // including myself
      if (this instanceof constructor) {
          return this;
      }
      if (!this.parent) {
          return null;
      }
      return this.parent.parentThatIsA(constructor);
  };
  
  Node.prototype.parentThatIsAnyOf = function (constructors) {
      // including myself
      var yup = false,
          myself = this;
      constructors.forEach(function (each) {
          if (myself.constructor === each) {
              yup = true;
              return;
          }
      });
      if (yup) {
          return this;
      }
      if (!this.parent) {
          return null;
      }
      return this.parent.parentThatIsAnyOf(constructors);
  };
  
  // Morphs //////////////////////////////////////////////////////////////
  
  // Morph: referenced constructors
  
  var Morph;
  var WorldMorph;
  var HandMorph;
  var ShadowMorph;
  var FrameMorph;
  var MenuMorph;
  var HandleMorph;
  var StringFieldMorph;
  var ColorPickerMorph;
  var SliderMorph;
  var ScrollFrameMorph;
  var InspectorMorph;
  var StringMorph;
  var TextMorph;
  
  // Morph inherits from Node:
  
  Morph.prototype = new Node();
  Morph.prototype.constructor = Morph;
  Morph.uber = Node.prototype;
  
  // Morph settings:
  
  /*
      damage list housekeeping
  
      the trackChanges property of the Morph prototype is a Boolean switch
      that determines whether the World's damage list ('broken' rectangles)
      tracks changes. By default the switch is always on. If set to false
      changes are not stored. This can be very useful for housekeeping of
      the damage list in situations where a large number of (sub-) morphs
      are changed more or less at once. Instead of keeping track of every
      single submorph's changes tremendous performance improvements can be
      achieved by setting the trackChanges flag to false before propagating
      the layout changes, setting it to true again and then storing the full
      bounds of the surrounding morph. As an example refer to the
  
          fixLayout()
  
      method of InspectorMorph, or the
  
          startLayout()
          endLayout()
  
      methods of SyntaxElementMorph in the Snap application.
  */
  
  Morph.prototype.trackChanges = true;
  Morph.prototype.shadowBlur = 4;
  
  // Morph instance creation:
  
  function Morph() {
      this.init();
  }
  
  // Morph initialization:
  
  Morph.prototype.init = function (noDraw) {
      Morph.uber.init.call(this);
      this.isMorph = true;
      this.image = null;
      this.bounds = new Rectangle(0, 0, 50, 40);
      this.cachedFullImage = null;
      this.cachedFullBounds = null;
      this.color = new Color(80, 80, 80);
      this.texture = null; // optional url of a fill-image
      this.cachedTexture = null; // internal cache of actual bg image
      this.alpha = 1;
      this.isVisible = true;
      this.isDraggable = false;
      this.isTemplate = false;
      this.acceptsDrops = false;
      this.noticesTransparentClick = false;
      if (!noDraw) {this.drawNew(); }
      this.fps = 0;
      this.customContextMenu = null;
      this.lastTime = Date.now();
      this.onNextStep = null; // optional function to be run once
  };
  
  // Morph string representation: e.g. 'a Morph 2 [20@45 | 130@250]'
  
  Morph.prototype.toString = function () {
      return 'a ' +
          (this.constructor.name ||
              this.constructor.toString().split(' ')[1].split('(')[0]) +
          ' ' +
          this.children.length.toString() + ' ' +
          this.bounds;
  };
  
  // Morph deleting:
  
  Morph.prototype.destroy = function () {
      if (this.parent !== null) {
          this.fullChanged();
          this.parent.removeChild(this);
      }
  };
  
  // Morph stepping:
  
  Morph.prototype.stepFrame = function () {
      if (!this.step) {
          return null;
      }
      var current, elapsed, leftover, nxt;
      current = Date.now();
      elapsed = current - this.lastTime;
      if (this.fps > 0) {
          leftover = (1000 / this.fps) - elapsed;
      } else {
          leftover = 0;
      }
      if (leftover < 1) {
          this.lastTime = current;
          if (this.onNextStep) {
              nxt = this.onNextStep;
              this.onNextStep = null;
              nxt.call(this);
          }
          this.step();
          this.children.forEach(function (child) {
              child.stepFrame();
          });
      }
  };
  
  Morph.prototype.nextSteps = function (arrayOfFunctions) {
      var lst = arrayOfFunctions || [],
          nxt = lst.shift(),
          myself = this;
      if (nxt) {
          this.onNextStep = function () {
              nxt.call(myself);
              myself.nextSteps(lst);
          };
      }
  };
  
  Morph.prototype.step = nop;
  
  // Morph accessing - geometry getting:
  
  Morph.prototype.left = function () {
      return this.bounds.left();
  };
  
  Morph.prototype.right = function () {
      return this.bounds.right();
  };
  
  Morph.prototype.top = function () {
      return this.bounds.top();
  };
  
  Morph.prototype.bottom = function () {
      return this.bounds.bottom();
  };
  
  Morph.prototype.center = function () {
      return this.bounds.center();
  };
  
  Morph.prototype.bottomCenter = function () {
      return this.bounds.bottomCenter();
  };
  
  Morph.prototype.bottomLeft = function () {
      return this.bounds.bottomLeft();
  };
  
  Morph.prototype.bottomRight = function () {
      return this.bounds.bottomRight();
  };
  
  Morph.prototype.boundingBox = function () {
      return this.bounds;
  };
  
  Morph.prototype.corners = function () {
      return this.bounds.corners();
  };
  
  Morph.prototype.leftCenter = function () {
      return this.bounds.leftCenter();
  };
  
  Morph.prototype.rightCenter = function () {
      return this.bounds.rightCenter();
  };
  
  Morph.prototype.topCenter = function () {
      return this.bounds.topCenter();
  };
  
  Morph.prototype.topLeft = function () {
      return this.bounds.topLeft();
  };
  
  Morph.prototype.topRight = function () {
      return this.bounds.topRight();
  };
  Morph.prototype.position = function () {
      return this.bounds.origin;
  };
  
  Morph.prototype.extent = function () {
      return this.bounds.extent();
  };
  
  Morph.prototype.width = function () {
      return this.bounds.width();
  };
  
  Morph.prototype.height = function () {
      return this.bounds.height();
  };
  
  Morph.prototype.fullBounds = function () {
      var result;
      result = this.bounds;
      this.children.forEach(function (child) {
          if (child.isVisible) {
              result = result.merge(child.fullBounds());
          }
      });
      return result;
  };
  
  Morph.prototype.fullBoundsNoShadow = function () {
      // answer my full bounds but ignore any shadow
      var result;
      result = this.bounds;
      this.children.forEach(function (child) {
          if (!(child instanceof ShadowMorph) && (child.isVisible)) {
              result = result.merge(child.fullBounds());
          }
      });
      return result;
  };
  
  Morph.prototype.visibleBounds = function () {
      // answer which part of me is not clipped by a Frame
      var visible = this.bounds,
          frames = this.allParents().filter(function (p) {
              return p instanceof FrameMorph;
          });
      frames.forEach(function (f) {
          visible = visible.intersect(f.bounds);
      });
      return visible;
  };
  
  // Morph accessing - simple changes:
  
  Morph.prototype.moveBy = function (delta) {
      this.fullChanged();
      this.silentMoveBy(delta);
      this.fullChanged();
  };
  
  Morph.prototype.silentMoveBy = function (delta) {
      var children = this.children,
          i = children.length;
      this.bounds = this.bounds.translateBy(delta);
      if (this.cachedFullBounds) {
          this.cachedFullBounds = this.cachedFullBounds.translateBy(delta);
      }
      // ugly optimization avoiding forEach()
      for (i; i > 0; i -= 1) {
          children[i - 1].silentMoveBy(delta);
      }
  };
  
  Morph.prototype.setPosition = function (aPoint) {
      var delta = aPoint.subtract(this.topLeft());
      if ((delta.x !== 0) || (delta.y !== 0)) {
          this.moveBy(delta);
      }
  };
  
  Morph.prototype.silentSetPosition = function (aPoint) {
      var delta = aPoint.subtract(this.topLeft());
      if ((delta.x !== 0) || (delta.y !== 0)) {
          this.silentMoveBy(delta);
      }
  };
  
  Morph.prototype.setLeft = function (x) {
      this.setPosition(
          new Point(
              x,
              this.top()
          )
      );
  };
  
  Morph.prototype.setRight = function (x) {
      this.setPosition(
          new Point(
              x - this.width(),
              this.top()
          )
      );
  };
  
  Morph.prototype.setTop = function (y) {
      this.setPosition(
          new Point(
              this.left(),
              y
          )
      );
  };
  
  Morph.prototype.setBottom = function (y) {
      this.setPosition(
          new Point(
              this.left(),
              y - this.height()
          )
      );
  };
  
  Morph.prototype.setCenter = function (aPoint) {
      this.setPosition(
          aPoint.subtract(
              this.extent().floorDivideBy(2)
          )
      );
  };
  
  Morph.prototype.setFullCenter = function (aPoint) {
      this.setPosition(
          aPoint.subtract(
              this.fullBounds().extent().floorDivideBy(2)
          )
      );
  };
  
  Morph.prototype.keepWithin = function (aMorph) {
      // make sure I am completely within another Morph's bounds
      var leftOff, rightOff, topOff, bottomOff;
      rightOff = this.fullBounds().right() - aMorph.right();
      if (rightOff > 0) {
          this.moveBy(new Point(-rightOff, 0));
      }
      leftOff = this.fullBounds().left() - aMorph.left();
      if (leftOff < 0) {
          this.moveBy(new Point(-leftOff, 0));
      }
      bottomOff = this.fullBounds().bottom() - aMorph.bottom();
      if (bottomOff > 0) {
          this.moveBy(new Point(0, -bottomOff));
      }
      topOff = this.fullBounds().top() - aMorph.top();
      if (topOff < 0) {
          this.moveBy(new Point(0, -topOff));
      }
  };
  
  Morph.prototype.scrollIntoView = function () {
      var leftOff, rightOff, topOff, bottomOff,
          sf = this.parentThatIsA(ScrollFrameMorph);
      if (!sf) {return; }
      rightOff = Math.min(
          this.fullBounds().right() - sf.right(),
          sf.contents.right() - sf.right()
      );
      if (rightOff > 0) {
          sf.contents.moveBy(new Point(-rightOff, 0));
      }
      leftOff = this.fullBounds().left() - sf.left();
      if (leftOff < 0) {
          sf.contents.moveBy(new Point(-leftOff, 0));
      }
      topOff = this.fullBounds().top() - sf.top();
      if (topOff < 0) {
          sf.contents.moveBy(new Point(0, -topOff));
      }
      bottomOff = this.fullBounds().bottom() - sf.bottom();
      if (bottomOff > 0) {
          sf.contents.moveBy(new Point(0, -bottomOff));
      }
      sf.adjustScrollBars();
  };
  
  // Morph accessing - dimensional changes requiring a complete redraw
  
  Morph.prototype.setExtent = function (aPoint, silently) {
      // silently avoids redrawing the receiver
      if (silently) {
          this.silentSetExtent(aPoint);
          return;
      }
      if (!aPoint.eq(this.extent())) {
          this.changed();
          this.silentSetExtent(aPoint);
          this.changed();
          this.drawNew();
      }
  };
  
  Morph.prototype.silentSetExtent = function (aPoint) {
      var ext, newWidth, newHeight;
      ext = aPoint.round();
      newWidth = Math.max(ext.x, 0);
      newHeight = Math.max(ext.y, 0);
      this.bounds.corner = new Point(
          this.bounds.origin.x + newWidth,
          this.bounds.origin.y + newHeight
      );
  };
  
  Morph.prototype.setWidth = function (width) {
      this.setExtent(new Point(width || 0, this.height()));
  };
  
  Morph.prototype.silentSetWidth = function (width) {
      // do not drawNew() just yet
      var w = Math.max(Math.round(width || 0), 0);
      this.bounds.corner = new Point(
          this.bounds.origin.x + w,
          this.bounds.corner.y
      );
  };
  
  Morph.prototype.setHeight = function (height) {
      this.setExtent(new Point(this.width(), height || 0));
  };
  
  Morph.prototype.silentSetHeight = function (height) {
      // do not drawNew() just yet
      var h = Math.max(Math.round(height || 0), 0);
      this.bounds.corner = new Point(
          this.bounds.corner.x,
          this.bounds.origin.y + h
      );
  };
  
  Morph.prototype.setColor = function (aColor) {
      if (aColor) {
          if (!this.color.eq(aColor)) {
              this.color = aColor;
              this.changed();
              this.drawNew();
          }
      }
  };
  
  // Morph displaying:
  
  Morph.prototype.drawNew = function () {
      // initialize my surface property
      this.image = newCanvas(this.extent());
      var context = this.image.getContext('2d');
      context.fillStyle = this.color.toString();
  
      /*
          Chrome issue:
  
              when filling a rectangular area, versions of Chrome beginning with
              57.0.2987.133 start introducing vertical transparent stripes
              to the right of the rectangle.
              The following code replaces the original fillRect() call with
              an explicit almost-rectangular path that miraculously  makes
              sure the whole rectangle gets filled correctly.
  
          Important: This needs to be monitored in the future so we can
          revert to sane code once this Chrome issue has been resolved again.
      */
  
      // context.fillRect(0, 0, this.width(), this.height()); // taken out
  
      context.beginPath();
      context.moveTo(0, 0);
      context.lineTo(this.image.width, 0);
      context.lineTo(this.image.width, this.image.height);
      context.lineTo(0, this.image.height + 0.0001); // yeah, I luv Chrome!
      context.closePath();
      context.fill();
  
      if (this.cachedTexture) {
          this.drawCachedTexture();
      } else if (this.texture) {
          this.drawTexture(this.texture);
      }
  };
  
  Morph.prototype.drawTexture = function (url) {
      var myself = this;
      this.cachedTexture = new Image();
      this.cachedTexture.onload = function () {
          myself.drawCachedTexture();
      };
      this.cachedTexture.src = this.texture = url; // make absolute
  };
  
  Morph.prototype.drawCachedTexture = function () {
      var bg = this.cachedTexture,
          cols = Math.floor(this.image.width / bg.width),
          lines = Math.floor(this.image.height / bg.height),
          x,
          y,
          context = this.image.getContext('2d');
  
      for (y = 0; y <= lines; y += 1) {
          for (x = 0; x <= cols; x += 1) {
              context.drawImage(bg, x * bg.width, y * bg.height);
          }
      }
      this.changed();
  };
  
  /*
  Morph.prototype.drawCachedTexture = function () {
      var context = this.image.getContext('2d'),
          pattern = context.createPattern(this.cachedTexture, 'repeat');
      context.fillStyle = pattern;
      context.fillRect(0, 0, this.image.width, this.image.height);
      this.changed();
  };
  */
  
  Morph.prototype.drawOn = function (aCanvas, aRect) {
      var rectangle, area, delta, src, context, w, h, sl, st,
          pic = this.cachedFullImage || this.image,
          bounds = this.cachedFullBounds || this.bounds;
      if (!this.isVisible) {
          return null;
      }
      rectangle = aRect || bounds;
      area = rectangle.intersect(bounds);
      if (area.extent().gt(new Point(0, 0))) {
          delta = bounds.position().neg();
          src = area.copy().translateBy(delta);
          context = aCanvas.getContext('2d');
          context.globalAlpha = this.alpha;
  
          sl = src.left();
          st = src.top();
          w = Math.min(src.width(), pic.width - sl);
          h = Math.min(src.height(), pic.height - st);
  
          if (w < 1 || h < 1) {
              return null;
          }
  
          context.drawImage(
              pic,
              sl,
              st,
              w,
              h,
              area.left(),
              area.top(),
              w,
              h
          );
      }
  };
  
  Morph.prototype.fullDrawOn = function (aCanvas, aRect) {
      var rectangle;
      if (!this.isVisible) {
          return null;
      }
      rectangle = aRect || this.cachedFullBounds || this.fullBounds();
      this.drawOn(aCanvas, rectangle);
      if (this.cachedFullImage) {return; }
      this.children.forEach(function (child) {
          child.fullDrawOn(aCanvas, rectangle);
      });
  };
  
  Morph.prototype.hide = function () {
      this.isVisible = false;
      this.changed();
      this.children.forEach(function (child) {
          child.hide();
      });
  };
  
  Morph.prototype.show = function () {
      this.isVisible = true;
      this.changed();
      this.children.forEach(function (child) {
          child.show();
      });
  };
  
  Morph.prototype.toggleVisibility = function () {
      this.isVisible = (!this.isVisible);
      this.changed();
      this.children.forEach(function (child) {
          child.toggleVisibility();
      });
  };
  
  // Morph full image:
  
  Morph.prototype.fullImageClassic = function () {
      // use the cache since fullDrawOn() will
      var fb = this.cachedFullBounds || this.fullBounds(),
          img = newCanvas(fb.extent()),
          ctx = img.getContext('2d');
      ctx.translate(-fb.origin.x, -fb.origin.y);
      this.fullDrawOn(img, fb);
      img.globalAlpha = this.alpha;
      return img;
  };
  
  Morph.prototype.fullImage = function () {
      var img, ctx, fb;
      img = newCanvas(this.fullBounds().extent());
      ctx = img.getContext('2d');
      fb = this.fullBounds();
      this.allChildren().forEach(function (morph) {
          if (morph.isVisible) {
              ctx.globalAlpha = morph.alpha;
              if (morph.image.width && morph.image.height) {
                  ctx.drawImage(
                      morph.image,
                      morph.bounds.origin.x - fb.origin.x,
                      morph.bounds.origin.y - fb.origin.y
                  );
              }
          }
      });
      return img;
  };
  
  // Morph shadow:
  
  Morph.prototype.shadowImage = function (off, color) {
      // fallback for Windows Chrome-Shadow bug
      var fb, img, outline, sha, ctx,
          offset = off || new Point(7, 7),
          clr = color || new Color(0, 0, 0);
      fb = this.fullBounds().extent();
      img = this.fullImage();
      outline = newCanvas(fb);
      ctx = outline.getContext('2d');
      ctx.drawImage(img, 0, 0);
      ctx.globalCompositeOperation = 'destination-out';
      ctx.drawImage(
          img,
          -offset.x,
          -offset.y
      );
      sha = newCanvas(fb);
      ctx = sha.getContext('2d');
      ctx.drawImage(outline, 0, 0);
      ctx.globalCompositeOperation = 'source-atop';
      ctx.fillStyle = clr.toString();
      ctx.fillRect(0, 0, fb.x, fb.y);
      return sha;
  };
  
  Morph.prototype.shadowImageBlurred = function (off, color) {
      var fb, img, sha, ctx,
          offset = off || new Point(7, 7),
          blur = this.shadowBlur,
          clr = color || new Color(0, 0, 0);
      fb = this.fullBounds().extent().add(blur * 2);
      img = this.fullImage();
      sha = newCanvas(fb);
      ctx = sha.getContext('2d');
      ctx.shadowOffsetX = offset.x;
      ctx.shadowOffsetY = offset.y;
      ctx.shadowBlur = blur;
      ctx.shadowColor = clr.toString();
      ctx.drawImage(
          img,
          blur - offset.x,
          blur - offset.y
      );
      ctx.shadowOffsetX = 0;
      ctx.shadowOffsetY = 0;
      ctx.shadowBlur = 0;
      ctx.globalCompositeOperation = 'destination-out';
      ctx.drawImage(
          img,
          blur - offset.x,
          blur - offset.y
      );
      return sha;
  };
  
  Morph.prototype.shadow = function (off, a, color) {
      var shadow = new ShadowMorph(),
          offset = off || new Point(7, 7),
          alpha = a || ((a === 0) ? 0 : 0.2),
          fb = this.fullBounds();
      shadow.setExtent(fb.extent().add(this.shadowBlur * 2));
      if (useBlurredShadows && !MorphicPreferences.isFlat) {
          shadow.image = this.shadowImageBlurred(offset, color);
          shadow.alpha = alpha;
          shadow.setPosition(fb.origin.add(offset).subtract(this.shadowBlur));
      } else {
          shadow.image = this.shadowImage(offset, color);
          shadow.alpha = alpha;
          shadow.setPosition(fb.origin.add(offset));
      }
      return shadow;
  };
  
  Morph.prototype.addShadow = function (off, a, color) {
      var shadow,
          offset = off || new Point(7, 7),
          alpha = a || ((a === 0) ? 0 : 0.2);
      shadow = this.shadow(offset, alpha, color);
      this.addBack(shadow);
      this.fullChanged();
      return shadow;
  };
  
  Morph.prototype.getShadow = function () {
      var shadows;
      shadows = this.children.slice(0).reverse().filter(
          function (child) {
              return child instanceof ShadowMorph;
          }
      );
      if (shadows.length !== 0) {
          return shadows[0];
      }
      return null;
  };
  
  Morph.prototype.removeShadow = function () {
      var shadow = this.getShadow();
      if (shadow !== null) {
          this.fullChanged();
          this.removeChild(shadow);
      }
  };
  
  // Morph pen trails:
  
  Morph.prototype.penTrails = function () {
      // answer my pen trails canvas. default is to answer my image
      return this.image;
  };
  
  // Morph updating:
  
  Morph.prototype.changed = function () {
      if (this.trackChanges) {
          var w = this.root();
          if (w instanceof WorldMorph) {
              w.broken.push(this.visibleBounds().spread());
          }
      }
      if (this.parent) {
          this.parent.childChanged(this);
      }
  };
  
  Morph.prototype.fullChanged = function () {
      if (this.trackChanges) {
          var w = this.root();
          if (w instanceof WorldMorph) {
              w.broken.push(
                  (this.cachedFullBounds || this.fullBounds()).spread()
              );
          }
      }
  };
  
  Morph.prototype.childChanged = function () {
      // react to a change in one of my children,
      // default is to just pass this message on upwards
      // override this method for Morphs that need to adjust accordingly
      if (this.parent) {
          this.parent.childChanged(this);
      }
  };
  
  // Morph accessing - structure:
  
  Morph.prototype.world = function () {
      var root = this.root();
      if (root instanceof WorldMorph) {
          return root;
      }
      if (root instanceof HandMorph) {
          return root.world;
      }
      return null;
  };
  
  Morph.prototype.add = function (aMorph) {
      var owner = aMorph.parent;
      if (owner !== null) {
          owner.removeChild(aMorph);
      }
      this.addChild(aMorph);
  };
  
  Morph.prototype.addBack = function (aMorph) {
      var owner = aMorph.parent;
      if (owner !== null) {
          owner.removeChild(aMorph);
      }
      this.addChildFirst(aMorph);
  };
  
  Morph.prototype.topMorphAt = function (point) {
      var i, result;
      if (!this.isVisible) {return null; }
      for (i = this.children.length - 1; i >= 0; i -= 1) {
          result = this.children[i].topMorphAt(point);
          if (result) {return result; }
      }
      return this.bounds.containsPoint(point) &&
          (this.noticesTransparentClick || !this.isTransparentAt(point)) ? this
                : null;
  };
  
  Morph.prototype.topMorphSuchThat = function (predicate) {
      var next;
      if (predicate.call(null, this)) {
          next = detect(
              this.children.slice(0).reverse(),
              predicate
          );
          if (next) {
              return next.topMorphSuchThat(predicate);
          }
          return this;
      }
      return null;
  };
  
  Morph.prototype.overlappedMorphs = function () {
      //exclude the World
      var world = this.world(),
          fb = this.fullBounds(),
          myself = this,
          allParents = this.allParents(),
          allChildren = this.allChildren(),
          morphs;
  
      morphs = world.allChildren();
      return morphs.filter(function (m) {
          return m.isVisible &&
              m !== myself &&
              m !== world &&
              !contains(allParents, m) &&
              !contains(allChildren, m) &&
              m.fullBounds().intersects(fb);
      });
  };
  
  // Morph pixel access:
  
  Morph.prototype.getPixelColor = function (aPoint) {
      var point, context, data;
      point = aPoint.subtract(this.bounds.origin);
      context = this.image.getContext('2d');
      data = context.getImageData(point.x, point.y, 1, 1);
      return new Color(
          data.data[0],
          data.data[1],
          data.data[2],
          data.data[3] / 255
      );
  };
  
  Morph.prototype.isTransparentAt = function (aPoint) {
      var point, context, data;
      if (this.bounds.containsPoint(aPoint)) {
          if (this.texture) {
              return false;
          }
          point = aPoint.subtract(this.bounds.origin);
          context = this.image.getContext('2d');
          data = context.getImageData(
              Math.floor(point.x),
              Math.floor(point.y),
              1,
              1
          );
          return data.data[3] === 0;
      }
      return false;
  };
  
  // Morph duplicating:
  
  Morph.prototype.copy = function () {
      var c = copy(this);
      c.parent = null;
      c.children = [];
      c.bounds = this.bounds.copy();
      return c;
  };
  
  Morph.prototype.fullCopy = function () {
      /*
      Produce a copy of me with my entire tree of submorphs. Morphs
      mentioned more than once are all directed to a single new copy.
      Other properties are also *shallow* copied, so you must override
      to deep copy Arrays and (complex) Objects
      */
      var map = new Map(), c;
      c = this.copyRecordingReferences(map);
      c.forAllChildren(function (m) {
          m.updateReferences(map);
      });
      return c;
  };
  
  Morph.prototype.copyRecordingReferences = function (map) {
      /*
      Recursively copy this entire composite morph, recording the
      correspondence between old and new morphs in the given dictionary.
      This dictionary will be used to update intra-composite references
      in the copy. See updateReferences().
  
      Note: This default implementation copies ONLY morphs. If a morph
      stores morphs in other properties that it wants to copy, then it
      should override this method to do so. The same goes for morphs that
      contain other complex data that should be copied when the morph is
      duplicated.
      */
      var c = this.copy();
      map.set(this, c);
      this.children.forEach(function (m) {
          c.add(m.copyRecordingReferences(map));
      });
      return c;
  };
  
  Morph.prototype.updateReferences = function (map) {
      /*
      Update intra-morph references within a composite morph that has
      been copied. For example, if a button refers to morph X in the
      orginal composite then the copy of that button in the new composite
      should refer to the copy of X in new composite, not the original X.
      */
      var properties = Object.keys(this),
          l = properties.length,
          property,
          value,
          reference,
          i;
      for (i = 0; i < l; i += 1) {
          property = properties[i];
          value = this[property];
          if (value && value.isMorph) {
              reference = map.get(value);
              if (reference) { this[property] = reference; }
          }
      }
  };
  
  // Morph dragging and dropping:
  
  Morph.prototype.rootForGrab = function () {
      if (this instanceof ShadowMorph) {
          return this.parent.rootForGrab();
      }
      if (this.parent instanceof ScrollFrameMorph) {
          return this.parent;
      }
      if (this.parent === null ||
              this.parent instanceof WorldMorph ||
              this.parent instanceof FrameMorph ||
              this.isDraggable === true) {
          return this;
      }
      return this.parent.rootForGrab();
  };
  
  Morph.prototype.isCorrectingOutsideDrag = function () {
      // make sure I don't "trail behind" the hand when dragged
      // override for morphs that you want to be dragged outside
      // their full bounds
      return true;
  };
  
  Morph.prototype.wantsDropOf = function (aMorph) {
      // default is to answer the general flag - change for my heirs
      if ((aMorph instanceof HandleMorph) ||
              (aMorph instanceof MenuMorph) ||
              (aMorph instanceof InspectorMorph)) {
          return false;
      }
      return this.acceptsDrops;
  };
  
  Morph.prototype.pickUp = function (wrrld) {
      var world = wrrld || this.world();
      this.setPosition(
          world.hand.position().subtract(
              this.extent().floorDivideBy(2)
          )
      );
      world.hand.grab(this);
  };
  
  Morph.prototype.isPickedUp = function () {
      return this.parentThatIsA(HandMorph) !== null;
  };
  
  Morph.prototype.situation = function () {
      // answer a dictionary specifying where I am right now, so
      // I can slide back to it if I'm dropped somewhere else
      if (this.parent) {
          return {
              origin: this.parent,
              position: this.position().subtract(this.parent.position())
          };
      }
      return null;
  };
  
  Morph.prototype.slideBackTo = function (
      situation,
      msecs,
      onBeforeDrop,
      onComplete
  ) {
      var pos = situation.origin.position().add(situation.position),
          myself = this;
      this.glideTo(
          pos,
          msecs,
          null, // easing
          function () {
              situation.origin.add(myself);
              if (onBeforeDrop) {onBeforeDrop(); }
              if (myself.justDropped) {myself.justDropped(); }
              if (situation.origin.reactToDropOf) {
                  situation.origin.reactToDropOf(myself);
              }
              if (onComplete) {onComplete(); }
          }
      );
  };
  
  // Morph animating:
  
  Morph.prototype.glideTo = function (endPoint, msecs, easing, onComplete) {
      var world = this.world(),
          myself = this;
      world.animations.push(new Animation(
          function (x) {myself.setLeft(x); },
          function () {return myself.left(); },
          -(this.left() - endPoint.x),
          msecs || 100,
          easing,
          onComplete
      ));
      world.animations.push(new Animation(
          function (y) {myself.setTop(y); },
          function () {return myself.top(); },
          -(this.top() - endPoint.y),
          msecs || 100,
          easing
      ));
  };
  
  Morph.prototype.fadeTo = function (endAlpha, msecs, easing, onComplete) {
      // include all my children, restore all original transparencies
      // on completion, so I can be recovered
      var world = this.world(),
          myself = this,
          oldAlpha = this.alpha;
      this.children.forEach(function (child) {
          child.fadeTo(endAlpha, msecs, easing);
      });
      world.animations.push(new Animation(
          function (n) {
              myself.alpha = n;
              myself.changed();
          },
          function () {return myself.alpha; },
          endAlpha - this.alpha,
          msecs || 200,
          easing,
          function () {
              myself.alpha = oldAlpha;
              if (onComplete) {onComplete(); }
          }
      ));
  };
  
  Morph.prototype.perish = function (msecs, onComplete) {
      var myself = this;
      this.fadeTo(
          0,
          msecs || 100,
          null,
          function () {
              myself.destroy();
              if (onComplete) {onComplete(); }
          }
      );
  };
  
  // Morph utilities:
  
  Morph.prototype.nop = nop;
  
  Morph.prototype.resize = function () {
      this.world().activeHandle = new HandleMorph(this);
  };
  
  Morph.prototype.move = function () {
      this.world().activeHandle = new HandleMorph(
          this,
          null,
          null,
          null,
          null,
          'move'
      );
  };
  
  Morph.prototype.moveCenter = function () {
      this.world().activeHandle = new HandleMorph(
          this,
          null,
          null,
          null,
          null,
          'moveCenter'
      );
  };
  
  Morph.prototype.hint = function (msg) {
      var m, text;
      text = msg;
      if (msg) {
          if (msg.toString) {
              text = msg.toString();
          }
      } else {
          text = 'NULL';
      }
      m = new MenuMorph(this, text);
      m.isDraggable = true;
      m.popUpCenteredAtHand(this.world());
  };
  
  Morph.prototype.inform = function (msg) {
      var m, text;
      text = msg;
      if (msg) {
          if (msg.toString) {
              text = msg.toString();
          }
      } else {
          text = 'NULL';
      }
      m = new MenuMorph(this, text);
      m.addItem("Ok");
      m.isDraggable = true;
      m.popUpCenteredAtHand(this.world());
  };
  
  Morph.prototype.prompt = function (
      msg,
      callback,
      environment,
      defaultContents,
      width,
      floorNum,
      ceilingNum,
      isRounded
  ) {
      var menu, entryField, slider, isNumeric;
      if (ceilingNum) {
          isNumeric = true;
      }
      menu = new MenuMorph(
          callback || null,
          msg || '',
          environment || null
      );
      entryField = new StringFieldMorph(
          defaultContents || '',
          width || 100,
          MorphicPreferences.prompterFontSize,
          MorphicPreferences.prompterFontName,
          false,
          false,
          isNumeric
      );
      menu.items.push(entryField);
      if (ceilingNum || MorphicPreferences.useSliderForInput) {
          slider = new SliderMorph(
              floorNum || 0,
              ceilingNum,
              parseFloat(defaultContents),
              Math.floor((ceilingNum - floorNum) / 4),
              'horizontal'
          );
          slider.alpha = 1;
          slider.color = new Color(225, 225, 225);
          slider.button.color = menu.borderColor;
          slider.button.highlightColor = slider.button.color.copy();
          slider.button.highlightColor.b += 100;
          slider.button.pressColor = slider.button.color.copy();
          slider.button.pressColor.b += 150;
          slider.setHeight(MorphicPreferences.prompterSliderSize);
          if (isRounded) {
              slider.action = function (num) {
                  entryField.changed();
                  entryField.text.text = Math.round(num).toString();
                  entryField.text.drawNew();
                  entryField.text.changed();
                  entryField.text.edit();
              };
          } else {
              slider.action = function (num) {
                  entryField.changed();
                  entryField.text.text = num.toString();
                  entryField.text.drawNew();
                  entryField.text.changed();
              };
          }
          menu.items.push(slider);
      }
  
      menu.addLine(2);
      menu.addItem('Ok', function () {
          return entryField.string();
      });
      menu.addItem('Cancel', function () {
          return null;
      });
      menu.isDraggable = true;
      menu.popUpAtHand(this.world());
      entryField.text.edit();
  };
  
  Morph.prototype.pickColor = function (
      msg,
      callback,
      environment,
      defaultContents
  ) {
      var menu, colorPicker;
      menu = new MenuMorph(
          callback || null,
          msg || '',
          environment || null
      );
      colorPicker = new ColorPickerMorph(defaultContents);
      menu.items.push(colorPicker);
      menu.addLine(2);
      menu.addItem('Ok', function () {
          return colorPicker.getChoice();
      });
      menu.addItem('Cancel', function () {
          return null;
      });
      menu.isDraggable = true;
      menu.popUpAtHand(this.world());
  };
  
  Morph.prototype.inspect = function (anotherObject) {
      var world = this.world instanceof Function ?
              this.world() : this.root() || this.world,
          inspector,
          inspectee = this;
  
      if (anotherObject) {
          inspectee = anotherObject;
      }
      inspector = new InspectorMorph(inspectee);
      inspector.setPosition(world.hand.position());
      inspector.keepWithin(world);
      world.add(inspector);
      inspector.changed();
  };
  
  // Morph menus:
  
  Morph.prototype.contextMenu = function () {
      var world;
  
      if (this.customContextMenu) {
          return this.customContextMenu;
      }
      world = this.world instanceof Function ? this.world() : this.world;
      if (world && world.isDevMode) {
          if (this.parent === world) {
              return this.developersMenu();
          }
          return this.hierarchyMenu();
      }
      return this.userMenu() ||
          (this.parent && this.parent.userMenu());
  };
  
  Morph.prototype.hierarchyMenu = function () {
      var parents = this.allParents(),
          world = this.world instanceof Function ? this.world() : this.world,
          menu = new MenuMorph(this, null);
  
      parents.forEach(function (each) {
          if (each.developersMenu && (each !== world)) {
              menu.addMenu(
                  each.toString().slice(0, 50),
                  each.developersMenu()
              );
          /*
              menu.addItem(each.toString().slice(0, 50), function () {
                  each.developersMenu().popUpAtHand(world);
              });
          */
          }
      });
      return menu;
  };
  
  Morph.prototype.developersMenu = function () {
      // 'name' is not an official property of a function, hence:
      var world = this.world instanceof Function ? this.world() : this.world,
          userMenu = this.userMenu() ||
              (this.parent && this.parent.userMenu()),
          menu = new MenuMorph(this, this.constructor.name ||
              this.constructor.toString().split(' ')[1].split('(')[0]);
      if (userMenu) {
          menu.addMenu('user features', userMenu);
          menu.addLine();
      }
      menu.addItem(
          "color...",
          function () {
              this.pickColor(
                  menu.title + localize('\ncolor:'),
                  this.setColor,
                  this,
                  this.color
              );
          },
          'choose another color \nfor this morph'
      );
      menu.addItem(
          "transparency...",
          function () {
              this.prompt(
                  menu.title + localize('\nalpha\nvalue:'),
                  this.setAlphaScaled,
                  this,
                  (this.alpha * 100).toString(),
                  null,
                  1,
                  100,
                  true
              );
          },
          'set this morph\'s\nalpha value'
      );
      menu.addItem(
          "resize...",
          'resize',
          'show a handle\nwhich can be dragged\nto change this morph\'s' +
              ' extent'
      );
      menu.addLine();
      menu.addItem(
          "duplicate",
          function () {
              this.fullCopy().pickUp(this.world());
          },
          'make a copy\nand pick it up'
      );
      menu.addItem(
          "pick up",
          'pickUp',
          'detach and put \ninto the hand'
      );
      menu.addItem(
          "attach...",
          'attach',
          'stick this morph\nto another one'
      );
      menu.addItem(
          "move...",
          'move',
          'show a handle\nwhich can be dragged\nto move this morph'
      );
      menu.addItem(
          "inspect...",
          'inspect',
          'open a window\non all properties'
      );
      menu.addItem(
          "pic...",
          function () {
              window.open(this.fullImageClassic().toDataURL());
          },
          'open a new window\nwith a picture of this morph'
      );
      menu.addLine();
      if (this.isDraggable) {
          menu.addItem(
              "lock",
              'toggleIsDraggable',
              'make this morph\nunmovable'
          );
      } else {
          menu.addItem(
              "unlock",
              'toggleIsDraggable',
              'make this morph\nmovable'
          );
      }
      menu.addItem("hide", 'hide');
      menu.addItem("delete", 'destroy');
      if (!(this instanceof WorldMorph)) {
          menu.addLine();
          menu.addItem(
              "World...",
              function () {
                  world.contextMenu().popUpAtHand(world);
              },
              'show the\nWorld\'s menu'
          );
      }
      return menu;
  };
  
  Morph.prototype.userMenu = function () {
      return null;
  };
  
  // Morph menu actions
  
  Morph.prototype.setAlphaScaled = function (alpha) {
      // for context menu demo purposes
      var newAlpha, unscaled;
      if (typeof alpha === 'number') {
          unscaled = alpha / 100;
          this.alpha = Math.min(Math.max(unscaled, 0.1), 1);
      } else {
          newAlpha = parseFloat(alpha);
          if (!isNaN(newAlpha)) {
              unscaled = newAlpha / 100;
              this.alpha = Math.min(Math.max(unscaled, 0.1), 1);
          }
      }
      this.changed();
  };
  
  Morph.prototype.attach = function () {
      var choices = this.overlappedMorphs(),
          menu = new MenuMorph(this, 'choose new parent:'),
          myself = this;
  
      choices.forEach(function (each) {
          menu.addItem(each.toString().slice(0, 50), function () {
              each.add(myself);
              myself.isDraggable = false;
          });
      });
      if (choices.length > 0) {
          menu.popUpAtHand(this.world());
      }
  };
  
  Morph.prototype.toggleIsDraggable = function () {
      // for context menu demo purposes
      this.isDraggable = !this.isDraggable;
  };
  
  Morph.prototype.colorSetters = function () {
      // for context menu demo purposes
      return ['color'];
  };
  
  Morph.prototype.numericalSetters = function () {
      // for context menu demo purposes
      return [
          'setLeft',
          'setTop',
          'setWidth',
          'setHeight',
          'setAlphaScaled'
      ];
  };
  
  // Morph entry field tabbing:
  
  Morph.prototype.allEntryFields = function () {
      return this.allChildren().filter(function (each) {
          return each.isEditable &&
              (each instanceof StringMorph ||
                  each instanceof TextMorph);
      });
  };
  
  Morph.prototype.nextEntryField = function (current) {
      var fields = this.allEntryFields(),
          idx = fields.indexOf(current);
      if (idx !== -1) {
          if (fields.length > idx + 1) {
              return fields[idx + 1];
          }
      }
      return fields[0];
  };
  
  Morph.prototype.previousEntryField = function (current) {
      var fields = this.allEntryFields(),
          idx = fields.indexOf(current);
      if (idx !== -1) {
          if (idx > 0) {
              return fields[idx - 1];
          }
          return fields[fields.length - 1];
      }
      return fields[0];
  };
  
  Morph.prototype.tab = function (editField) {
  /*
      the <tab> key was pressed in one of my edit fields.
      invoke my "nextTab()" function if it exists, else
      propagate it up my owner chain.
  */
      if (this.nextTab) {
          this.nextTab(editField);
      } else if (this.parent) {
          this.parent.tab(editField);
      }
  };
  
  Morph.prototype.backTab = function (editField) {
  /*
      the <back tab> key was pressed in one of my edit fields.
      invoke my "previousTab()" function if it exists, else
      propagate it up my owner chain.
  */
      if (this.previousTab) {
          this.previousTab(editField);
      } else if (this.parent) {
          this.parent.backTab(editField);
      }
  };
  
  /*
      the following are examples of what the navigation methods should
      look like. Insert these at the World level for fallback, and at lower
      levels in the Morphic tree (e.g. dialog boxes) for a more fine-grained
      control over the tabbing cycle.
  
  Morph.prototype.nextTab = function (editField) {
      var next = this.nextEntryField(editField);
      editField.clearSelection();
      next.selectAll();
      next.edit();
  };
  
  Morph.prototype.previousTab = function (editField) {
      var prev = this.previousEntryField(editField);
      editField.clearSelection();
      prev.selectAll();
      prev.edit();
  };
  
  */
  
  // Morph events:
  
  Morph.prototype.escalateEvent = function (functionName, arg) {
      var handler = this.parent;
      while (!handler[functionName] && handler.parent !== null) {
          handler = handler.parent;
      }
      if (handler[functionName]) {
          handler[functionName](arg);
      }
  };
  
  // Morph eval:
  
  Morph.prototype.evaluateString = function (code) {
      var result;
  
      try {
          result = eval(code);
          this.drawNew();
          this.changed();
      } catch (err) {
          this.inform(err);
      }
      return result;
  };
  
  // Morph collision detection:
  
  Morph.prototype.isTouching = function (otherMorph) {
      var oImg = this.overlappingImage(otherMorph),
          data;
      if (!oImg.width || !oImg.height) {
          return false;
      }
      data = oImg.getContext('2d')
          .getImageData(1, 1, oImg.width, oImg.height)
          .data;
      return detect(
          data,
          function (each) {
              return each !== 0;
          }
      ) !== null;
  };
  
  Morph.prototype.overlappingImage = function (otherMorph) {
      var fb = this.fullBounds(),
          otherFb = otherMorph.fullBounds(),
          oRect = fb.intersect(otherFb),
          oImg = newCanvas(oRect.extent()),
          ctx = oImg.getContext('2d');
      if (oRect.width() < 1 || oRect.height() < 1) {
          return newCanvas(new Point(1, 1));
      }
      ctx.drawImage(
          this.fullImage(),
          oRect.origin.x - fb.origin.x,
          oRect.origin.y - fb.origin.y
      );
      ctx.globalCompositeOperation = 'source-in';
      ctx.drawImage(
          otherMorph.fullImage(),
          otherFb.origin.x - oRect.origin.x,
          otherFb.origin.y - oRect.origin.y
      );
      return oImg;
  };
  
  // ShadowMorph /////////////////////////////////////////////////////////
  
  // ShadowMorph inherits from Morph:
  
  ShadowMorph.prototype = new Morph();
  ShadowMorph.prototype.constructor = ShadowMorph;
  ShadowMorph.uber = Morph.prototype;
  
  // ShadowMorph instance creation:
  
  function ShadowMorph() {
      this.init();
  }
  
  ShadowMorph.prototype.topMorphAt = function () {
      return null;
  };
  
  // HandleMorph ////////////////////////////////////////////////////////
  
  // I am a resize / move handle that can be attached to any Morph
  
  // HandleMorph inherits from Morph:
  
  HandleMorph.prototype = new Morph();
  HandleMorph.prototype.constructor = HandleMorph;
  HandleMorph.uber = Morph.prototype;
  
  // HandleMorph instance creation:
  
  function HandleMorph(target, minX, minY, insetX, insetY, type) {
      // if insetY is missing, it will be the same as insetX
      this.init(target, minX, minY, insetX, insetY, type);
  }
  
  HandleMorph.prototype.init = function (
      target,
      minX,
      minY,
      insetX,
      insetY,
      type
  ) {
      var size = MorphicPreferences.handleSize;
      this.target = target || null;
      this.minExtent = new Point(minX || 0, minY || 0);
      this.inset = new Point(insetX || 0, insetY || insetX || 0);
      this.type =  type || 'resize'; // also: 'move', 'moveCenter', 'movePivot'
      HandleMorph.uber.init.call(this);
      this.color = new Color(255, 255, 255);
      this.isDraggable = false;
      this.noticesTransparentClick = true;
      if (this.type === 'movePivot') {
          size *= 2;
      }
      this.setExtent(new Point(size, size));
  };
  
  // HandleMorph drawing:
  
  HandleMorph.prototype.drawNew = function () {
      this.normalImage = newCanvas(this.extent());
      this.highlightImage = newCanvas(this.extent());
      if (this.type === 'movePivot') {
          this.drawCrosshairsOnCanvas(this.normalImage, 0.6);
          this.drawCrosshairsOnCanvas(this.highlightImage, 0.5);
      } else {
          this.drawOnCanvas(
              this.normalImage,
              this.color,
              new Color(100, 100, 100)
          );
          this.drawOnCanvas(
              this.highlightImage,
              new Color(100, 100, 255),
              new Color(255, 255, 255)
          );
      }
      this.image = this.normalImage;
      if (this.target) {
          if (this.type === 'moveCenter') {
              this.setCenter(this.target.center());
          } else if (this.type === 'movePivot') {
              this.setCenter(this.target.rotationCenter());
          } else { // 'resize', 'move'
              this.setPosition(
                  this.target.bottomRight().subtract(
                      this.extent().add(this.inset)
                  )
              );
          }
          this.target.add(this);
          this.target.changed();
      }
  };
  
  HandleMorph.prototype.drawCrosshairsOnCanvas = function (aCanvas, fract) {
      var ctx = aCanvas.getContext('2d'),
          r = aCanvas.width / 2;
      ctx.fillStyle = 'rgba(255, 255, 255, 0.5)';
      ctx.arc(r, r, r * 0.9, radians(0), radians(360), false);
      ctx.fill();
      ctx.strokeStyle = 'black';
      ctx.lineWidth = 1;
      ctx.beginPath();
      ctx.arc(r, r, r * fract, radians(0), radians(360), false);
      ctx.stroke();
      ctx.moveTo(0, r);
      ctx.lineTo(aCanvas.width, r);
      ctx.stroke();
      ctx.moveTo(r, 0);
      ctx.lineTo(r, aCanvas.height);
      ctx.stroke();
  };
  
  HandleMorph.prototype.drawOnCanvas = function (
      aCanvas,
      color,
      shadowColor
  ) {
      var context = aCanvas.getContext('2d'),
          isSquare = (this.type.indexOf('move') === 0),
          p1,
          p11,
          p2,
          p22,
          i;
  
      context.lineWidth = 1;
      context.lineCap = 'round';
  
      context.strokeStyle = color.toString();
  
      if (isSquare) {
  
          p1 = this.bottomLeft().subtract(this.position());
          p11 = p1.copy();
          p2 = this.topRight().subtract(this.position());
          p22 = p2.copy();
  
          for (i = 0; i <= this.height(); i = i + 6) {
              p11.y = p1.y - i;
              p22.y = p2.y - i;
  
              context.beginPath();
              context.moveTo(p11.x, p11.y);
              context.lineTo(p22.x, p22.y);
              context.closePath();
              context.stroke();
          }
      }
  
      p1 = this.bottomLeft().subtract(this.position());
      p11 = p1.copy();
      p2 = this.topRight().subtract(this.position());
      p22 = p2.copy();
  
      for (i = 0; i <= this.width(); i = i + 6) {
          p11.x = p1.x + i;
          p22.x = p2.x + i;
  
          context.beginPath();
          context.moveTo(p11.x, p11.y);
          context.lineTo(p22.x, p22.y);
          context.closePath();
          context.stroke();
      }
  
      context.strokeStyle = shadowColor.toString();
  
      if (isSquare) {
  
          p1 = this.bottomLeft().subtract(this.position());
          p11 = p1.copy();
          p2 = this.topRight().subtract(this.position());
          p22 = p2.copy();
  
          for (i = -2; i <= this.height(); i = i + 6) {
              p11.y = p1.y - i;
              p22.y = p2.y - i;
  
              context.beginPath();
              context.moveTo(p11.x, p11.y);
              context.lineTo(p22.x, p22.y);
              context.closePath();
              context.stroke();
          }
      }
  
      p1 = this.bottomLeft().subtract(this.position());
      p11 = p1.copy();
      p2 = this.topRight().subtract(this.position());
      p22 = p2.copy();
  
      for (i = 2; i <= this.width(); i = i + 6) {
          p11.x = p1.x + i;
          p22.x = p2.x + i;
  
          context.beginPath();
          context.moveTo(p11.x, p11.y);
          context.lineTo(p22.x, p22.y);
          context.closePath();
          context.stroke();
      }
  };
  
  // HandleMorph stepping:
  
  HandleMorph.prototype.step = null;
  
  HandleMorph.prototype.mouseDownLeft = function (pos) {
      var world = this.root(),
          offset,
          myself = this;
  
      if (!this.target) {
          return null;
      }
      if (this.type.indexOf('move') === 0) {
          offset = pos.subtract(this.center());
      } else {
          offset = pos.subtract(this.bounds.origin);
      }
      this.step = function () {
          var newPos, newExt;
          if (world.hand.mouseButton) {
              newPos = world.hand.bounds.origin.copy().subtract(offset);
              if (this.type === 'resize') {
                  newExt = newPos.add(
                      myself.extent().add(myself.inset)
                  ).subtract(myself.target.bounds.origin);
                  newExt = newExt.max(myself.minExtent);
                  myself.target.setExtent(newExt);
  
                  myself.setPosition(
                      myself.target.bottomRight().subtract(
                          myself.extent().add(myself.inset)
                      )
                  );
              } else if (this.type === 'moveCenter') {
                  myself.target.setCenter(newPos);
              } else if (this.type === 'movePivot') {
                  myself.target.setPivot(newPos);
                  myself.setCenter(this.target.rotationCenter());
              } else { // type === 'move'
                  myself.target.setPosition(
                      newPos.subtract(this.target.extent())
                          .add(this.extent())
                  );
              }
          } else {
              this.step = null;
          }
      };
      if (!this.target.step) {
          this.target.step = function () {
              nop();
          };
      }
  };
  
  // HandleMorph dragging and dropping:
  
  HandleMorph.prototype.rootForGrab = function () {
      return this;
  };
  
  // HandleMorph events:
  
  HandleMorph.prototype.mouseEnter = function () {
      this.image = this.highlightImage;
      this.changed();
  };
  
  HandleMorph.prototype.mouseLeave = function () {
      this.image = this.normalImage;
      this.changed();
  };
  
  // HandleMorph menu:
  
  HandleMorph.prototype.attach = function () {
      var choices = this.overlappedMorphs(),
          menu = new MenuMorph(this, 'choose target:'),
          myself = this;
  
      choices.forEach(function (each) {
          menu.addItem(each.toString().slice(0, 50), function () {
              myself.isDraggable = false;
              myself.target = each;
              myself.drawNew();
              myself.noticesTransparentClick = true;
          });
      });
      if (choices.length > 0) {
          menu.popUpAtHand(this.world());
      }
  };
  
  // PenMorph ////////////////////////////////////////////////////////////
  
  // I am a simple LOGO-wise turtle.
  
  // PenMorph: referenced constructors
  
  var PenMorph;
  
  // PenMorph inherits from Morph:
  
  PenMorph.prototype = new Morph();
  PenMorph.prototype.constructor = PenMorph;
  PenMorph.uber = Morph.prototype;
  
  // PenMorph instance creation:
  
  function PenMorph() {
      this.init();
  }
  
  PenMorph.prototype.init = function () {
      var size = MorphicPreferences.handleSize * 4;
  
      // additional properties:
      this.isWarped = false; // internal optimization
      this.heading = 0;
      this.isDown = true;
      this.size = 1;
      this.wantsRedraw = false;
      this.penPoint = 'tip'; // or 'center"
      this.penBounds = null; // rect around the visible arrow shape
  
      HandleMorph.uber.init.call(this);
      this.setExtent(new Point(size, size));
  };
  
  // PenMorph updating - optimized for warping, i.e atomic recursion
  
  PenMorph.prototype.changed = function () {
      if (this.isWarped === false) {
          var w = this.root();
          if (w instanceof WorldMorph) {
              w.broken.push(this.visibleBounds().spread());
          }
          if (this.parent) {
              this.parent.childChanged(this);
          }
      }
  };
  
  // PenMorph display:
  
  PenMorph.prototype.drawNew = function (facing) {
      // my orientation can be overridden with the "facing" parameter to
      // implement Scratch-style rotation styles
  
      var context, start, dest, left, right, len,
          direction = facing || this.heading;
  
      if (this.isWarped) {
          this.wantsRedraw = true;
          return;
      }
      this.image = newCanvas(this.extent());
      context = this.image.getContext('2d');
      len = this.width() / 2;
      start = this.center().subtract(this.bounds.origin);
  
      if (this.penPoint === 'tip') {
          dest = start.distanceAngle(len * 0.75, direction - 180);
          left = start.distanceAngle(len, direction + 195);
          right = start.distanceAngle(len, direction - 195);
      } else { // 'middle'
          dest = start.distanceAngle(len * 0.75, direction);
          left = start.distanceAngle(len * 0.33, direction + 230);
          right = start.distanceAngle(len * 0.33, direction - 230);
      }
  
      // cache penBounds
      this.penBounds = new Rectangle(
          Math.min(start.x, dest.x, left.x, right.x),
          Math.min(start.y, dest.y, left.y, right.y),
          Math.max(start.x, dest.x, left.x, right.x),
          Math.max(start.y, dest.y, left.y, right.y)
      );
  
      // draw arrow shape
      context.fillStyle = this.color.toString();
      context.beginPath();
  
      context.moveTo(start.x, start.y);
      context.lineTo(left.x, left.y);
      context.lineTo(dest.x, dest.y);
      context.lineTo(right.x, right.y);
  
      context.closePath();
      context.strokeStyle = 'white';
      context.lineWidth = 3;
      context.stroke();
      context.strokeStyle = 'black';
      context.lineWidth = 1;
      context.stroke();
      context.fill();
  };
  
  // PenMorph access:
  
  PenMorph.prototype.setHeading = function (degrees) {
      this.heading = ((+degrees % 360) + 360) % 360;
      this.drawNew();
      this.changed();
  };
  
  // PenMorph drawing:
  
  PenMorph.prototype.drawLine = function (start, dest) {
      var context = this.parent.penTrails().getContext('2d'),
          from = start.subtract(this.parent.bounds.origin),
          to = dest.subtract(this.parent.bounds.origin);
      if (this.isDown) {
          context.lineWidth = this.size;
          context.strokeStyle = this.color.toString();
          context.lineCap = 'round';
          context.lineJoin = 'round';
          context.beginPath();
          context.moveTo(from.x, from.y);
          context.lineTo(to.x, to.y);
          context.stroke();
          if (this.isWarped === false) {
              this.world().broken.push(
                  start.rectangle(dest).expandBy(
                      Math.max(this.size / 2, 1)
                  ).intersect(this.parent.visibleBounds()).spread()
              );
          }
      }
  };
  
  // PenMorph turtle ops:
  
  PenMorph.prototype.turn = function (degrees) {
      this.setHeading(this.heading + parseFloat(degrees));
  };
  
  PenMorph.prototype.forward = function (steps) {
      var start = this.center(),
          dest,
          dist = parseFloat(steps);
      if (dist >= 0) {
          dest = this.position().distanceAngle(dist, this.heading);
      } else {
          dest = this.position().distanceAngle(
              Math.abs(dist),
              (this.heading - 180)
          );
      }
      this.setPosition(dest);
      this.drawLine(start, this.center());
  };
  
  PenMorph.prototype.down = function () {
      this.isDown = true;
  };
  
  PenMorph.prototype.up = function () {
      this.isDown = false;
  };
  
  PenMorph.prototype.clear = function () {
      this.parent.drawNew();
      this.parent.changed();
  };
  
  // PenMorph optimization for atomic recursion:
  
  PenMorph.prototype.startWarp = function () {
      this.wantsRedraw = false;
      this.isWarped = true;
  };
  
  PenMorph.prototype.endWarp = function () {
      this.isWarped = false;
      if (this.wantsRedraw) {
          this.drawNew();
          this.wantsRedraw = false;
      }
      this.parent.changed();
  };
  
  PenMorph.prototype.warp = function (fun) {
      this.startWarp();
      fun.call(this);
      this.endWarp();
  };
  
  PenMorph.prototype.warpOp = function (selector, argsArray) {
      this.startWarp();
      this[selector].apply(this, argsArray);
      this.endWarp();
  };
  
  // PenMorph demo ops:
  // try these with WARP eg.: this.warp(function () {tree(12, 120, 20)})
  
  PenMorph.prototype.warpSierpinski = function (length, min) {
      this.warpOp('sierpinski', [length, min]);
  };
  
  PenMorph.prototype.sierpinski = function (length, min) {
      var i;
      if (length > min) {
          for (i = 0; i < 3; i += 1) {
              this.sierpinski(length * 0.5, min);
              this.turn(120);
              this.forward(length);
          }
      }
  };
  
  PenMorph.prototype.warpTree = function (level, length, angle) {
      this.warpOp('tree', [level, length, angle]);
  };
  
  PenMorph.prototype.tree = function (level, length, angle) {
      if (level > 0) {
          this.size = level;
          this.forward(length);
          this.turn(angle);
          this.tree(level - 1, length * 0.75, angle);
          this.turn(angle * -2);
          this.tree(level - 1, length * 0.75, angle);
          this.turn(angle);
          this.forward(-length);
      }
  };
  
  // ColorPaletteMorph ///////////////////////////////////////////////////
  
  var ColorPaletteMorph;
  
  // ColorPaletteMorph inherits from Morph:
  
  ColorPaletteMorph.prototype = new Morph();
  ColorPaletteMorph.prototype.constructor = ColorPaletteMorph;
  ColorPaletteMorph.uber = Morph.prototype;
  
  // ColorPaletteMorph instance creation:
  
  function ColorPaletteMorph(target, sizePoint) {
      this.init(
          target || null,
          sizePoint || new Point(80, 50)
      );
  }
  
  ColorPaletteMorph.prototype.init = function (target, size) {
      ColorPaletteMorph.uber.init.call(this);
      this.target = target;
      this.targetSetter = 'color';
      this.silentSetExtent(size);
      this.choice = null;
      this.drawNew();
  };
  
  ColorPaletteMorph.prototype.drawNew = function () {
      var context, ext, x, y, h, l;
  
      ext = this.extent();
      this.image = newCanvas(this.extent());
      context = this.image.getContext('2d');
      this.choice = new Color();
      for (x = 0; x <= ext.x; x += 1) {
          h = 360 * x / ext.x;
          for (y = 0; y <= ext.y; y += 1) {
              l = 100 - (y / ext.y * 100);
              context.fillStyle = 'hsl(' + h + ',100%,' + l + '%)';
              context.fillRect(x, y, 1, 1);
          }
      }
  };
  
  ColorPaletteMorph.prototype.mouseMove = function (pos) {
      this.choice = this.getPixelColor(pos);
      this.updateTarget();
  };
  
  ColorPaletteMorph.prototype.mouseDownLeft = function (pos) {
      this.choice = this.getPixelColor(pos);
      this.updateTarget();
  };
  
  ColorPaletteMorph.prototype.updateTarget = function () {
      if (this.target instanceof Morph && this.choice !== null) {
          if (this.target[this.targetSetter] instanceof Function) {
              this.target[this.targetSetter](this.choice);
          } else {
              this.target[this.targetSetter] = this.choice;
              this.target.drawNew();
              this.target.changed();
          }
      }
  };
  
  // ColorPaletteMorph menu:
  
  ColorPaletteMorph.prototype.developersMenu = function () {
      var menu = ColorPaletteMorph.uber.developersMenu.call(this);
      menu.addLine();
      menu.addItem(
          'set target',
          "setTarget",
          'choose another morph\nwhose color property\n will be' +
              ' controlled by this one'
      );
      return menu;
  };
  
  ColorPaletteMorph.prototype.setTarget = function () {
      var choices = this.overlappedMorphs(),
          menu = new MenuMorph(this, 'choose target:'),
          myself = this;
  
      choices.push(this.world());
      choices.forEach(function (each) {
          menu.addItem(each.toString().slice(0, 50), function () {
              myself.target = each;
              myself.setTargetSetter();
          });
      });
      if (choices.length === 1) {
          this.target = choices[0];
          this.setTargetSetter();
      } else if (choices.length > 0) {
          menu.popUpAtHand(this.world());
      }
  };
  
  ColorPaletteMorph.prototype.setTargetSetter = function () {
      var choices = this.target.colorSetters(),
          menu = new MenuMorph(this, 'choose target property:'),
          myself = this;
  
      choices.forEach(function (each) {
          menu.addItem(each, function () {
              myself.targetSetter = each;
          });
      });
      if (choices.length === 1) {
          this.targetSetter = choices[0];
      } else if (choices.length > 0) {
          menu.popUpAtHand(this.world());
      }
  };
  
  // GrayPaletteMorph ///////////////////////////////////////////////////
  
  var GrayPaletteMorph;
  
  // GrayPaletteMorph inherits from ColorPaletteMorph:
  
  GrayPaletteMorph.prototype = new ColorPaletteMorph();
  GrayPaletteMorph.prototype.constructor = GrayPaletteMorph;
  GrayPaletteMorph.uber = ColorPaletteMorph.prototype;
  
  // GrayPaletteMorph instance creation:
  
  function GrayPaletteMorph(target, sizePoint) {
      this.init(
          target || null,
          sizePoint || new Point(80, 10)
      );
  }
  
  GrayPaletteMorph.prototype.drawNew = function () {
      var context, ext, gradient;
  
      ext = this.extent();
      this.image = newCanvas(this.extent());
      context = this.image.getContext('2d');
      this.choice = new Color();
      gradient = context.createLinearGradient(0, 0, ext.x, ext.y);
      gradient.addColorStop(0, 'black');
      gradient.addColorStop(1, 'white');
      context.fillStyle = gradient;
      context.fillRect(0, 0, ext.x, ext.y);
  };
  
  // ColorPickerMorph ///////////////////////////////////////////////////
  
  // ColorPickerMorph inherits from Morph:
  
  ColorPickerMorph.prototype = new Morph();
  ColorPickerMorph.prototype.constructor = ColorPickerMorph;
  ColorPickerMorph.uber = Morph.prototype;
  
  // ColorPickerMorph instance creation:
  
  function ColorPickerMorph(defaultColor) {
      this.init(defaultColor || new Color(255, 255, 255));
  }
  
  ColorPickerMorph.prototype.init = function (defaultColor) {
      this.choice = defaultColor;
      ColorPickerMorph.uber.init.call(this);
      this.color = new Color(255, 255, 255);
      this.silentSetExtent(new Point(80, 80));
      this.drawNew();
  };
  
  ColorPickerMorph.prototype.drawNew = function () {
      ColorPickerMorph.uber.drawNew.call(this);
      this.buildSubmorphs();
  };
  
  ColorPickerMorph.prototype.buildSubmorphs = function () {
      var cpal, gpal, x, y;
  
      this.children.forEach(function (child) {
          child.destroy();
      });
      this.children = [];
      this.feedback = new Morph();
      this.feedback.color = this.choice;
      this.feedback.setExtent(new Point(20, 20));
      cpal = new ColorPaletteMorph(
          this.feedback,
          new Point(this.width(), 50)
      );
      gpal = new GrayPaletteMorph(
          this.feedback,
          new Point(this.width(), 5)
      );
      cpal.setPosition(this.bounds.origin);
      this.add(cpal);
      gpal.setPosition(cpal.bottomLeft());
      this.add(gpal);
      x = (gpal.left() +
          Math.floor((gpal.width() - this.feedback.width()) / 2));
      y = gpal.bottom() + Math.floor((this.bottom() -
          gpal.bottom() - this.feedback.height()) / 2);
      this.feedback.setPosition(new Point(x, y));
      this.add(this.feedback);
  };
  
  ColorPickerMorph.prototype.getChoice = function () {
      return this.feedback.color;
  };
  
  ColorPickerMorph.prototype.rootForGrab = function () {
      return this;
  };
  
  // BlinkerMorph ////////////////////////////////////////////////////////
  
  // can be used for text cursors
  
  var BlinkerMorph;
  
  // BlinkerMorph inherits from Morph:
  
  BlinkerMorph.prototype = new Morph();
  BlinkerMorph.prototype.constructor = BlinkerMorph;
  BlinkerMorph.uber = Morph.prototype;
  
  // BlinkerMorph instance creation:
  
  function BlinkerMorph(rate) {
      this.init(rate);
  }
  
  BlinkerMorph.prototype.init = function (rate) {
      BlinkerMorph.uber.init.call(this);
      this.color = new Color(0, 0, 0);
      this.fps = rate || 2;
      this.drawNew();
  };
  
  // BlinkerMorph stepping:
  
  BlinkerMorph.prototype.step = function () {
      this.toggleVisibility();
  };
  
  // CursorMorph /////////////////////////////////////////////////////////
  
  // I am a String/Text editing widget
  
  // CursorMorph: referenced constructors
  
  var CursorMorph;
  
  // CursorMorph inherits from BlinkerMorph:
  
  CursorMorph.prototype = new BlinkerMorph();
  CursorMorph.prototype.constructor = CursorMorph;
  CursorMorph.uber = BlinkerMorph.prototype;
  
  // CursorMorph preferences settings:
  
  CursorMorph.prototype.viewPadding = 1;
  
  // CursorMorph instance creation:
  
  function CursorMorph(aStringOrTextMorph) {
      this.init(aStringOrTextMorph);
  }
  
  CursorMorph.prototype.init = function (aStringOrTextMorph) {
      var ls;
  
      // additional properties:
      this.keyDownEventUsed = false;
      this.target = aStringOrTextMorph;
      this.originalContents = this.target.text;
      this.originalAlignment = this.target.alignment;
      this.slot = this.target.text.length;
      CursorMorph.uber.init.call(this);
      ls = fontHeight(this.target.fontSize);
      this.setExtent(new Point(Math.max(Math.floor(ls / 20), 1), ls));
      this.drawNew();
      this.image.getContext('2d').font = this.target.font();
      if (this.target instanceof TextMorph &&
              (this.target.alignment !== 'left')) {
          this.target.setAlignmentToLeft();
      }
      this.gotoSlot(this.slot);
      this.initializeClipboardHandler();
  };
  
  CursorMorph.prototype.initializeClipboardHandler = function () {
      // Add hidden text box for copying and pasting
      var myself = this,
          wrrld = this.target.world();
  
      this.clipboardHandler = document.createElement('textarea');
      this.clipboardHandler.style.position = 'absolute';
      this.clipboardHandler.style.top = window.outerHeight;
      this.clipboardHandler.style.right = '101%'; // placed just out of view
  
      document.body.appendChild(this.clipboardHandler);
  
      this.clipboardHandler.value = this.target.selection();
      this.clipboardHandler.focus();
      this.clipboardHandler.select();
  
      this.clipboardHandler.addEventListener(
          'keypress',
          function (event) {
              myself.processKeyPress(event);
              this.value = myself.target.selection();
              this.select();
          },
          false
      );
  
      this.clipboardHandler.addEventListener(
          'keydown',
          function (event) {
              myself.processKeyDown(event);
              if (event.shiftKey) {
                  wrrld.currentKey = 16;
              }
              this.value = myself.target.selection();
              this.select();
  
              // Make sure tab prevents default
              if (event.key === 'U+0009' ||
                      event.key === 'Tab') {
                  myself.processKeyPress(event);
                  event.preventDefault();
              }
          },
          false
      );
  
      this.clipboardHandler.addEventListener(
          'keyup',
          function (event) {
              wrrld.currentKey = null;
          },
          false
      );
  
      this.clipboardHandler.addEventListener(
          'input',
          function (event) {
              if (this.value === '') {
                  myself.gotoSlot(myself.target.selectionStartSlot());
                  myself.target.deleteSelection();
              }
          },
          false
      );
  };
  
  // CursorMorph event processing:
  
  CursorMorph.prototype.processKeyPress = function (event) {
      // this.inspectKeyEvent(event);
      if (this.keyDownEventUsed) {
          this.keyDownEventUsed = false;
          return null;
      }
      if ((event.keyCode === 40) || event.charCode === 40) {
          this.insert('(');
          return null;
      }
      if ((event.keyCode === 37) || event.charCode === 37) {
          this.insert('%');
          return null;
      }
      if (event.keyCode) { // Opera doesn't support charCode
          if (event.ctrlKey && (!event.altKey)) {
              this.ctrl(event.keyCode, event.shiftKey);
          } else if (event.metaKey) {
              this.cmd(event.keyCode, event.shiftKey);
          } else {
              this.insert(
                  String.fromCharCode(event.keyCode),
                  event.shiftKey
              );
          }
      } else if (event.charCode) { // all other browsers
          if (event.ctrlKey && (!event.altKey)) {
              this.ctrl(event.charCode, event.shiftKey);
          } else if (event.metaKey) {
              this.cmd(event.charCode, event.shiftKey);
          } else {
              this.insert(
                  String.fromCharCode(event.charCode),
                  event.shiftKey
              );
          }
      }
      // notify target's parent of key event
      this.target.escalateEvent('reactToKeystroke', event);
  };
  
  CursorMorph.prototype.processKeyDown = function (event) {
      // this.inspectKeyEvent(event);
      var shift = event.shiftKey,
          wordNavigation = event.ctrlKey || event.altKey,
          selecting = this.target.selection().length > 0;
  
      this.keyDownEventUsed = false;
      if (event.ctrlKey && (!event.altKey)) {
          this.ctrl(event.keyCode, event.shiftKey);
          // notify target's parent of key event
          this.target.escalateEvent('reactToKeystroke', event);
      }
      if (event.metaKey) {
          this.cmd(event.keyCode, event.shiftKey);
          // notify target's parent of key event
          this.target.escalateEvent('reactToKeystroke', event);
      }
  
      switch (event.keyCode) {
      case 37:
          if (selecting && !shift && !wordNavigation) {
              this.gotoSlot(Math.min(this.target.startMark, this.target.endMark));
              this.target.clearSelection();
          } else {
              this.goLeft(
                      shift,
                      wordNavigation ?
                          this.slot - this.target.previousWordFrom(this.slot)
                          : 1);
          }
          this.keyDownEventUsed = true;
          break;
      case 39:
          if (selecting && !shift && !wordNavigation) {
              this.gotoSlot(Math.max(this.target.startMark, this.target.endMark));
              this.target.clearSelection();
          } else {
              this.goRight(
                      shift,
                      wordNavigation ?
                          this.target.nextWordFrom(this.slot) - this.slot
                          : 1);
          }
          this.keyDownEventUsed = true;
          break;
      case 38:
          this.goUp(shift);
          this.keyDownEventUsed = true;
          break;
      case 40:
          this.goDown(shift);
          this.keyDownEventUsed = true;
          break;
      case 36:
          this.goHome(shift);
          this.keyDownEventUsed = true;
          break;
      case 35:
          this.goEnd(shift);
          this.keyDownEventUsed = true;
          break;
      case 46:
          this.deleteRight();
          this.keyDownEventUsed = true;
          break;
      case 8:
          this.deleteLeft();
          this.keyDownEventUsed = true;
          break;
      case 13:
          if ((this.target instanceof StringMorph) || shift) {
              this.accept();
          } else {
              this.insert('\n');
          }
          this.keyDownEventUsed = true;
          break;
      case 27:
          this.cancel();
          this.keyDownEventUsed = true;
          break;
      default:
          nop();
          // this.inspectKeyEvent(event);
      }
      // notify target's parent of key event
      this.target.escalateEvent('reactToKeystroke', event);
  };
  
  // CursorMorph navigation:
  
  /*
  // original non-scrolling code, commented out in case we need to fall back:
  
  CursorMorph.prototype.gotoSlot = function (newSlot) {
      this.setPosition(this.target.slotPosition(newSlot));
      this.slot = Math.max(newSlot, 0);
  };
  */
  
  CursorMorph.prototype.gotoSlot = function (slot) {
      var length = this.target.text.length,
          pos = this.target.slotPosition(slot),
          right,
          left;
      this.slot = slot < 0 ? 0 : slot > length ? length : slot;
      if (this.parent && this.target.isScrollable) {
          right = this.parent.right() - this.viewPadding;
          left = this.parent.left() + this.viewPadding;
          if (pos.x > right) {
              this.target.setLeft(this.target.left() + right - pos.x);
              pos.x = right;
          }
          if (pos.x < left) {
              left = Math.min(this.parent.left(), left);
              this.target.setLeft(this.target.left() + left - pos.x);
              pos.x = left;
          }
          if (this.target.right() < right &&
                  right - this.target.width() < left) {
              pos.x += right - this.target.right();
              this.target.setRight(right);
          }
      }
      this.show();
      this.setPosition(pos);
      if (this.parent
              && this.parent.parent instanceof ScrollFrameMorph
              && this.target.isScrollable) {
          this.parent.parent.scrollCursorIntoView(this);
      }
  };
  
  CursorMorph.prototype.goLeft = function (shift, howMany) {
      this.updateSelection(shift);
      this.gotoSlot(this.slot - (howMany || 1));
      this.updateSelection(shift);
  };
  
  CursorMorph.prototype.goRight = function (shift, howMany) {
      this.updateSelection(shift);
      this.gotoSlot(this.slot + (howMany || 1));
      this.updateSelection(shift);
  };
  
  CursorMorph.prototype.goUp = function (shift) {
      this.updateSelection(shift);
      this.gotoSlot(this.target.upFrom(this.slot));
      this.updateSelection(shift);
  };
  
  CursorMorph.prototype.goDown = function (shift) {
      this.updateSelection(shift);
      this.gotoSlot(this.target.downFrom(this.slot));
      this.updateSelection(shift);
  };
  
  CursorMorph.prototype.goHome = function (shift) {
      this.updateSelection(shift);
      this.gotoSlot(this.target.startOfLine(this.slot));
      this.updateSelection(shift);
  };
  
  CursorMorph.prototype.goEnd = function (shift) {
      this.updateSelection(shift);
      this.gotoSlot(this.target.endOfLine(this.slot));
      this.updateSelection(shift);
  };
  
  CursorMorph.prototype.gotoPos = function (aPoint) {
      this.gotoSlot(this.target.slotAt(aPoint));
      this.show();
  };
  
  // CursorMorph selecting:
  
  CursorMorph.prototype.updateSelection = function (shift) {
      if (shift) {
          if (isNil(this.target.endMark) && isNil(this.target.startMark)) {
              this.target.startMark = this.slot;
              this.target.endMark = this.slot;
          } else if (this.target.endMark !== this.slot) {
              this.target.endMark = this.slot;
              this.target.drawNew();
              this.target.changed();
          }
      } else {
          this.target.clearSelection();
      }
  };
  
  // CursorMorph editing:
  
  CursorMorph.prototype.accept = function () {
      var world = this.root();
      if (world) {
          world.stopEditing();
      }
      this.escalateEvent('accept', this);
  };
  
  CursorMorph.prototype.cancel = function () {
      var world = this.root();
      this.undo();
      if (world) {
          world.stopEditing();
      }
      this.escalateEvent('cancel', this);
  };
  
  CursorMorph.prototype.undo = function () {
      this.target.text = this.originalContents;
      this.target.changed();
      this.target.drawNew();
      this.target.changed();
      this.gotoSlot(0);
  };
  
  CursorMorph.prototype.insert = function (aChar, shiftKey) {
      var text;
      if (aChar === '\u0009') {
          this.target.escalateEvent('reactToEdit', this.target);
          if (shiftKey) {
              return this.target.backTab(this.target);
          }
          return this.target.tab(this.target);
      }
      if (!this.target.isNumeric ||
              !isNaN(parseFloat(aChar)) ||
              contains(['-', '.'], aChar)) {
          if (this.target.selection() !== '') {
              this.gotoSlot(this.target.selectionStartSlot());
              this.target.deleteSelection();
          }
          text = this.target.text;
          text = text.slice(0, this.slot) +
              aChar +
              text.slice(this.slot);
          this.target.text = text;
          this.target.drawNew();
          this.target.changed();
          this.goRight(false, aChar.length);
      }
  };
  
  CursorMorph.prototype.ctrl = function (aChar, shiftKey) {
      if (aChar === 64 || (aChar === 65 && shiftKey)) {
          this.insert('@');
      } else if (aChar === 65) {
          this.target.selectAll();
      } else if (aChar === 90) {
          this.undo();
      } else if (aChar === 123) {
          this.insert('{');
      } else if (aChar === 125) {
          this.insert('}');
      } else if (aChar === 91) {
          this.insert('[');
      } else if (aChar === 93) {
          this.insert(']');
      } else if (!isNil(this.target.receiver)) {
          if (aChar === 68) {
              this.target.doIt();
          } else if (aChar === 73) {
              this.target.inspectIt();
          } else if (aChar === 80) {
              this.target.showIt();
          }
      }
  
  
  };
  
  CursorMorph.prototype.cmd = function (aChar, shiftKey) {
      if (aChar === 64 || (aChar === 65 && shiftKey)) {
          this.insert('@');
      } else if (aChar === 65) {
          this.target.selectAll();
      } else if (aChar === 90) {
          this.undo();
      } else if (!isNil(this.target.receiver)) {
          if (aChar === 68) {
              this.target.doIt();
          } else if (aChar === 73) {
              this.target.inspectIt();
          } else if (aChar === 80) {
              this.target.showIt();
          }
      }
  };
  
  CursorMorph.prototype.deleteRight = function () {
      var text;
      if (this.target.selection() !== '') {
          this.gotoSlot(this.target.selectionStartSlot());
          this.target.deleteSelection();
      } else {
          text = this.target.text;
          this.target.changed();
          text = text.slice(0, this.slot) + text.slice(this.slot + 1);
          this.target.text = text;
          this.target.drawNew();
      }
  };
  
  CursorMorph.prototype.deleteLeft = function () {
      var text;
      if (this.target.selection()) {
          this.gotoSlot(this.target.selectionStartSlot());
          return this.target.deleteSelection();
      }
      text = this.target.text;
      this.target.changed();
      this.target.text = text.substring(0, this.slot - 1) +
          text.substr(this.slot);
      this.target.drawNew();
      this.goLeft();
  };
  
  // CursorMorph destroying:
  
  CursorMorph.prototype.destroy = function () {
      if (this.target.alignment !== this.originalAlignment) {
          this.target.alignment = this.originalAlignment;
          this.target.drawNew();
          this.target.changed();
      }
      this.destroyClipboardHandler();
      CursorMorph.uber.destroy.call(this);
  };
  
  CursorMorph.prototype.destroyClipboardHandler = function () {
      var nodes = document.body.children,
          each,
          i;
      if (this.clipboardHandler) {
          for (i = 0; i < nodes.length; i += 1) {
              each = nodes[i];
              if (each === this.clipboardHandler) {
                  document.body.removeChild(this.clipboardHandler);
                  this.clipboardHandler = null;
              }
          }
      }
  };
  
  // CursorMorph utilities:
  
  CursorMorph.prototype.inspectKeyEvent = function (event) {
      // private
      this.inform(
          'Key pressed: ' +
              String.fromCharCode(event.charCode) +
              '\n------------------------' +
              '\ncharCode: ' +
              event.charCode.toString() +
              '\nkeyCode: ' +
              event.keyCode.toString() +
              '\nshiftKey: ' +
              event.shiftKey.toString() +
              '\naltKey: ' +
              event.altKey.toString() +
              '\nctrlKey: ' +
              event.ctrlKey.toString() +
              '\ncmdKey: ' +
              event.metaKey.toString()
      );
  };
  
  // BoxMorph ////////////////////////////////////////////////////////////
  
  // I can have an optionally rounded border
  
  var BoxMorph;
  
  // BoxMorph inherits from Morph:
  
  BoxMorph.prototype = new Morph();
  BoxMorph.prototype.constructor = BoxMorph;
  BoxMorph.uber = Morph.prototype;
  
  // BoxMorph instance creation:
  
  function BoxMorph(edge, border, borderColor) {
      this.init(edge, border, borderColor);
  }
  
  BoxMorph.prototype.init = function (edge, border, borderColor) {
      this.edge = edge || 4;
      this.border = border || ((border === 0) ? 0 : 2);
      this.borderColor = borderColor || new Color();
      BoxMorph.uber.init.call(this);
  };
  
  // BoxMorph drawing:
  
  BoxMorph.prototype.drawNew = function () {
      var context;
  
      this.image = newCanvas(this.extent());
      context = this.image.getContext('2d');
      if ((this.edge === 0) && (this.border === 0)) {
          BoxMorph.uber.drawNew.call(this);
          return null;
      }
      context.fillStyle = this.color.toString();
      context.beginPath();
      this.outlinePath(
          context,
          Math.max(this.edge - this.border, 0),
          this.border
      );
      context.closePath();
      context.fill();
      if (this.border > 0) {
          context.lineWidth = this.border;
          context.strokeStyle = this.borderColor.toString();
          context.beginPath();
          this.outlinePath(context, this.edge, this.border / 2);
          context.closePath();
          context.stroke();
      }
  };
  
  BoxMorph.prototype.outlinePath = function (context, radius, inset) {
      var offset = radius + inset,
          w = this.width(),
          h = this.height();
  
      // top left:
      context.arc(
          offset,
          offset,
          radius,
          radians(-180),
          radians(-90),
          false
      );
      // top right:
      context.arc(
          w - offset,
          offset,
          radius,
          radians(-90),
          radians(-0),
          false
      );
      // bottom right:
      context.arc(
          w - offset,
          h - offset,
          radius,
          radians(0),
          radians(90),
          false
      );
      // bottom left:
      context.arc(
          offset,
          h - offset,
          radius,
          radians(90),
          radians(180),
          false
      );
  };
  
  
  // BoxMorph menus:
  
  BoxMorph.prototype.developersMenu = function () {
      var menu = BoxMorph.uber.developersMenu.call(this);
      menu.addLine();
      menu.addItem(
          "border width...",
          function () {
              this.prompt(
                  menu.title + '\nborder\nwidth:',
                  this.setBorderWidth,
                  this,
                  this.border.toString(),
                  null,
                  0,
                  100,
                  true
              );
          },
          'set the border\'s\nline size'
      );
      menu.addItem(
          "border color...",
          function () {
              this.pickColor(
                  menu.title + '\nborder color:',
                  this.setBorderColor,
                  this,
                  this.borderColor
              );
          },
          'set the border\'s\nline color'
      );
      menu.addItem(
          "corner size...",
          function () {
              this.prompt(
                  menu.title + '\ncorner\nsize:',
                  this.setCornerSize,
                  this,
                  this.edge.toString(),
                  null,
                  0,
                  100,
                  true
              );
          },
          'set the corner\'s\nradius'
      );
      return menu;
  };
  
  BoxMorph.prototype.setBorderWidth = function (size) {
      // for context menu demo purposes
      var newSize;
      if (typeof size === 'number') {
          this.border = Math.max(size, 0);
      } else {
          newSize = parseFloat(size);
          if (!isNaN(newSize)) {
              this.border = Math.max(newSize, 0);
          }
      }
      this.drawNew();
      this.changed();
  };
  
  BoxMorph.prototype.setBorderColor = function (color) {
      // for context menu demo purposes
      if (color) {
          this.borderColor = color;
          this.drawNew();
          this.changed();
      }
  };
  
  BoxMorph.prototype.setCornerSize = function (size) {
      // for context menu demo purposes
      var newSize;
      if (typeof size === 'number') {
          this.edge = Math.max(size, 0);
      } else {
          newSize = parseFloat(size);
          if (!isNaN(newSize)) {
              this.edge = Math.max(newSize, 0);
          }
      }
      this.drawNew();
      this.changed();
  };
  
  BoxMorph.prototype.colorSetters = function () {
      // for context menu demo purposes
      return ['color', 'borderColor'];
  };
  
  BoxMorph.prototype.numericalSetters = function () {
      // for context menu demo purposes
      var list = BoxMorph.uber.numericalSetters.call(this);
      list.push('setBorderWidth', 'setCornerSize');
      return list;
  };
  
  // SpeechBubbleMorph ///////////////////////////////////////////////////
  
  /*
      I am a comic-style speech bubble that can display either a string,
      a Morph, a Canvas or a toString() representation of anything else.
      If I am invoked using popUp() I behave like a tool tip.
  */
  
  // SpeechBubbleMorph: referenced constructors
  
  var SpeechBubbleMorph;
  
  // SpeechBubbleMorph inherits from BoxMorph:
  
  SpeechBubbleMorph.prototype = new BoxMorph();
  SpeechBubbleMorph.prototype.constructor = SpeechBubbleMorph;
  SpeechBubbleMorph.uber = BoxMorph.prototype;
  
  // SpeechBubbleMorph instance creation:
  
  function SpeechBubbleMorph(
      contents,
      color,
      edge,
      border,
      borderColor,
      padding,
      isThought
  ) {
      this.init(contents, color, edge, border, borderColor, padding, isThought);
  }
  
  SpeechBubbleMorph.prototype.init = function (
      contents,
      color,
      edge,
      border,
      borderColor,
      padding,
      isThought // bool or anything but "true" to draw no hook at all
  ) {
      this.isPointingRight = true; // orientation of text
      this.contents = contents || '';
      this.padding = padding || 0; // additional vertical pixels
      this.isThought = isThought || false; // draw "think" bubble
      this.isClickable = false;
      SpeechBubbleMorph.uber.init.call(
          this,
          edge || 6,
          border || ((border === 0) ? 0 : 1),
          borderColor || new Color(140, 140, 140)
      );
      this.color = color || new Color(230, 230, 230);
      this.drawNew();
  };
  
  // SpeechBubbleMorph invoking:
  
  SpeechBubbleMorph.prototype.popUp = function (world, pos, isClickable) {
      this.drawNew();
      this.setPosition(pos.subtract(new Point(0, this.height())));
      this.addShadow(new Point(2, 2), 80);
      this.keepWithin(world);
      world.add(this);
      this.fullChanged();
      world.hand.destroyTemporaries();
      world.hand.temporaries.push(this);
  
      if (!isClickable) {
          this.mouseEnter = function () {
              this.destroy();
          };
      } else {
          this.isClickable = true;
      }
  };
  
  // SpeechBubbleMorph drawing:
  
  SpeechBubbleMorph.prototype.drawNew = function () {
      // re-build my contents
      if (this.contentsMorph) {
          this.contentsMorph.destroy();
      }
      if (this.contents instanceof Morph) {
          this.contentsMorph = this.contents;
      } else if (isString(this.contents)) {
          this.contentsMorph = new TextMorph(
              this.contents,
              MorphicPreferences.bubbleHelpFontSize,
              null,
              false,
              true,
              'center'
          );
      } else if (this.contents instanceof HTMLCanvasElement) {
          this.contentsMorph = new Morph();
          this.contentsMorph.silentSetWidth(this.contents.width);
          this.contentsMorph.silentSetHeight(this.contents.height);
          this.contentsMorph.image = this.contents;
      } else {
          this.contentsMorph = new TextMorph(
              this.contents.toString(),
              MorphicPreferences.bubbleHelpFontSize,
              null,
              false,
              true,
              'center'
          );
      }
      this.add(this.contentsMorph);
  
      // adjust my layout
      this.silentSetWidth(this.contentsMorph.width() +
          (this.padding ? this.padding * 2 : this.edge * 2));
      this.silentSetHeight(this.contentsMorph.height() +
          this.edge +
          this.border * 2 +
          this.padding * 2 +
          2);
  
      // draw my outline
      SpeechBubbleMorph.uber.drawNew.call(this);
  
      // position my contents
      this.contentsMorph.setPosition(this.position().add(
          new Point(
              this.padding || this.edge,
              this.border + this.padding + 1
          )
      ));
  };
  
  SpeechBubbleMorph.prototype.outlinePath = function (
      context,
      radius,
      inset
  ) {
      var offset = radius + inset,
          w = this.width(),
          h = this.height(),
          rad;
  
      function circle(x, y, r) {
          context.moveTo(x + r, y);
          context.arc(x, y, r, radians(0), radians(360));
      }
  
      // top left:
      context.arc(
          offset,
          offset,
          radius,
          radians(-180),
          radians(-90),
          false
      );
      // top right:
      context.arc(
          w - offset,
          offset,
          radius,
          radians(-90),
          radians(-0),
          false
      );
      // bottom right:
      context.arc(
          w - offset,
          h - offset - radius,
          radius,
          radians(0),
          radians(90),
          false
      );
      if (!this.isThought) { // draw speech bubble hook
          if (this.isPointingRight) {
              context.lineTo(
                  offset + radius,
                  h - offset
              );
              context.lineTo(
                  radius / 2 + inset,
                  h - inset
              );
          } else { // pointing left
              context.lineTo(
                  w - (radius / 2 + inset),
                  h - inset
              );
              context.lineTo(
                  w - (offset + radius),
                  h - offset
              );
          }
      }
      // bottom left:
      context.arc(
          offset,
          h - offset - radius,
          radius,
          radians(90),
          radians(180),
          false
      );
      if (this.isThought === true) { // use anything but "true" to draw nothing
          // close large bubble:
          context.lineTo(
              inset,
              offset
          );
          // draw thought bubbles:
          if (this.isPointingRight) {
              // tip bubble:
              rad = radius / 4;
              circle(rad + inset, h - rad - inset, rad);
              // middle bubble:
              rad = radius / 3.2;
              circle(rad * 2 + inset, h - rad - inset * 2, rad);
              // top bubble:
              rad = radius / 2.8;
              circle(rad * 3 + inset * 2, h - rad - inset * 4, rad);
          } else { // pointing left
              // tip bubble:
              rad = radius / 4;
              circle(w - (rad + inset), h - rad - inset, rad);
              // middle bubble:
              rad = radius / 3.2;
              circle(w - (rad * 2 + inset), h - rad - inset * 2, rad);
              // top bubble:
              rad = radius / 2.8;
              circle(w - (rad * 3 + inset * 2), h - rad - inset * 4, rad);
          }
      }
  };
  
  // SpeechBubbleMorph shadow
  
  /*
      only take the 'plain' image, so the box rounding and the
      shadow doesn't become conflicted by embedded scrolling panes
  */
  
  SpeechBubbleMorph.prototype.shadowImage = function (off, color) {
      // fallback for Windows Chrome-Shadow bug
      var fb, img, outline, sha, ctx,
          offset = off || new Point(7, 7),
          clr = color || new Color(0, 0, 0);
      fb = this.extent();
      img = this.image;
      outline = newCanvas(fb);
      ctx = outline.getContext('2d');
      ctx.drawImage(img, 0, 0);
      ctx.globalCompositeOperation = 'destination-out';
      ctx.drawImage(
          img,
          -offset.x,
          -offset.y
      );
      sha = newCanvas(fb);
      ctx = sha.getContext('2d');
      ctx.drawImage(outline, 0, 0);
      ctx.globalCompositeOperation = 'source-atop';
      ctx.fillStyle = clr.toString();
      ctx.fillRect(0, 0, fb.x, fb.y);
      return sha;
  };
  
  SpeechBubbleMorph.prototype.shadowImageBlurred = function (off, color) {
      var fb, img, sha, ctx,
          offset = off || new Point(7, 7),
          blur = this.shadowBlur,
          clr = color || new Color(0, 0, 0);
      fb = this.extent().add(blur * 2);
      img = this.image;
      sha = newCanvas(fb);
      ctx = sha.getContext('2d');
      ctx.shadowOffsetX = offset.x;
      ctx.shadowOffsetY = offset.y;
      ctx.shadowBlur = blur;
      ctx.shadowColor = clr.toString();
      ctx.drawImage(
          img,
          blur - offset.x,
          blur - offset.y
      );
      ctx.shadowOffsetX = 0;
      ctx.shadowOffsetY = 0;
      ctx.shadowBlur = 0;
      ctx.globalCompositeOperation = 'destination-out';
      ctx.drawImage(
          img,
          blur - offset.x,
          blur - offset.y
      );
      return sha;
  };
  
  // SpeechBubbleMorph resizing
  
  SpeechBubbleMorph.prototype.fixLayout = function () {
      this.removeShadow();
      this.drawNew();
      this.addShadow(new Point(2, 2), 80);
  };
  
  // CircleBoxMorph //////////////////////////////////////////////////////
  
  // I can be used for sliders
  
  var CircleBoxMorph;
  
  // CircleBoxMorph inherits from Morph:
  
  CircleBoxMorph.prototype = new Morph();
  CircleBoxMorph.prototype.constructor = CircleBoxMorph;
  CircleBoxMorph.uber = Morph.prototype;
  
  function CircleBoxMorph(orientation) {
      this.init(orientation || 'vertical');
  }
  
  CircleBoxMorph.prototype.init = function (orientation) {
      CircleBoxMorph.uber.init.call(this);
      this.orientation = orientation;
      this.autoOrient = true;
      this.setExtent(new Point(20, 100));
  };
  
  CircleBoxMorph.prototype.autoOrientation = function () {
      if (this.height() > this.width()) {
          this.orientation = 'vertical';
      } else {
          this.orientation = 'horizontal';
      }
  };
  
  CircleBoxMorph.prototype.drawNew = function () {
      var radius, center1, center2, rect, points, x, y,
          context, ext,
          myself = this;
  
      if (this.autoOrient) {
          this.autoOrientation();
      }
      this.image = newCanvas(this.extent());
      context = this.image.getContext('2d');
  
      if (this.orientation === 'vertical') {
          radius = this.width() / 2;
          x = this.center().x;
          center1 = new Point(x, this.top() + radius);
          center2 = new Point(x, this.bottom() - radius);
          rect = this.bounds.origin.add(new Point(0, radius)).corner(
              this.bounds.corner.subtract(new Point(0, radius))
          );
      } else {
          radius = this.height() / 2;
          y = this.center().y;
          center1 = new Point(this.left() + radius, y);
          center2 = new Point(this.right() - radius, y);
          rect = this.bounds.origin.add(new Point(radius, 0)).corner(
              this.bounds.corner.subtract(new Point(radius, 0))
          );
      }
      points = [ center1.subtract(this.bounds.origin),
          center2.subtract(this.bounds.origin)];
      points.forEach(function (center) {
          context.fillStyle = myself.color.toString();
          context.beginPath();
          context.arc(
              center.x,
              center.y,
              radius,
              0,
              2 * Math.PI,
              false
          );
          context.closePath();
          context.fill();
      });
      rect = rect.translateBy(this.bounds.origin.neg());
      ext = rect.extent();
      if (ext.x > 0 && ext.y > 0) {
          context.fillRect(
              rect.origin.x,
              rect.origin.y,
              rect.width(),
              rect.height()
          );
      }
  };
  
  // CircleBoxMorph menu:
  
  CircleBoxMorph.prototype.developersMenu = function () {
      var menu = CircleBoxMorph.uber.developersMenu.call(this);
      menu.addLine();
      if (this.orientation === 'vertical') {
          menu.addItem(
              "horizontal...",
              'toggleOrientation',
              'toggle the\norientation'
          );
      } else {
          menu.addItem(
              "vertical...",
              'toggleOrientation',
              'toggle the\norientation'
          );
      }
      return menu;
  };
  
  CircleBoxMorph.prototype.toggleOrientation = function () {
      var center = this.center();
      this.changed();
      if (this.orientation === 'vertical') {
          this.orientation = 'horizontal';
      } else {
          this.orientation = 'vertical';
      }
      this.silentSetExtent(new Point(this.height(), this.width()));
      this.setCenter(center);
      this.drawNew();
      this.changed();
  };
  
  // SliderButtonMorph ///////////////////////////////////////////////////
  
  var SliderButtonMorph;
  
  // SliderButtonMorph inherits from CircleBoxMorph:
  
  SliderButtonMorph.prototype = new CircleBoxMorph();
  SliderButtonMorph.prototype.constructor = SliderButtonMorph;
  SliderButtonMorph.uber = CircleBoxMorph.prototype;
  
  function SliderButtonMorph(orientation) {
      this.init(orientation);
  }
  
  SliderButtonMorph.prototype.init = function (orientation) {
      this.color = new Color(80, 80, 80);
      this.highlightColor = new Color(90, 90, 140);
      this.pressColor = new Color(80, 80, 160);
      this.is3D = false;
      this.hasMiddleDip = true;
      SliderButtonMorph.uber.init.call(this, orientation);
  };
  
  SliderButtonMorph.prototype.autoOrientation = nop;
  
  SliderButtonMorph.prototype.drawNew = function () {
      var colorBak = this.color.copy();
  
      SliderButtonMorph.uber.drawNew.call(this);
      if (this.is3D || !MorphicPreferences.isFlat) {
          this.drawEdges();
      }
      this.normalImage = this.image;
  
      this.color = this.highlightColor.copy();
      SliderButtonMorph.uber.drawNew.call(this);
      if (this.is3D || !MorphicPreferences.isFlat) {
          this.drawEdges();
      }
      this.highlightImage = this.image;
  
      this.color = this.pressColor.copy();
      SliderButtonMorph.uber.drawNew.call(this);
      if (this.is3D || !MorphicPreferences.isFlat) {
          this.drawEdges();
      }
      this.pressImage = this.image;
  
      this.color = colorBak;
      this.image = this.normalImage;
  
  };
  
  SliderButtonMorph.prototype.drawEdges = function () {
      var context = this.image.getContext('2d'),
          gradient,
          radius,
          w = this.width(),
          h = this.height();
  
      context.lineJoin = 'round';
      context.lineCap = 'round';
  
      if (this.orientation === 'vertical') {
          context.lineWidth = w / 3;
          gradient = context.createLinearGradient(
              0,
              0,
              context.lineWidth,
              0
          );
          gradient.addColorStop(0, 'white');
          gradient.addColorStop(1, this.color.toString());
  
          context.strokeStyle = gradient;
          context.beginPath();
          context.moveTo(context.lineWidth * 0.5, w / 2);
          context.lineTo(context.lineWidth * 0.5, h - w / 2);
          context.stroke();
  
          gradient = context.createLinearGradient(
              w - context.lineWidth,
              0,
              w,
              0
          );
          gradient.addColorStop(0, this.color.toString());
          gradient.addColorStop(1, 'black');
  
          context.strokeStyle = gradient;
          context.beginPath();
          context.moveTo(w - context.lineWidth * 0.5, w / 2);
          context.lineTo(w - context.lineWidth * 0.5, h - w / 2);
          context.stroke();
  
          if (this.hasMiddleDip) {
              gradient = context.createLinearGradient(
                  context.lineWidth,
                  0,
                  w - context.lineWidth,
                  0
              );
  
              radius = w / 4;
              gradient.addColorStop(0, 'black');
              gradient.addColorStop(0.35, this.color.toString());
              gradient.addColorStop(0.65, this.color.toString());
              gradient.addColorStop(1, 'white');
  
              context.fillStyle = gradient;
              context.beginPath();
              context.arc(
                  w / 2,
                  h / 2,
                  radius,
                  radians(0),
                  radians(360),
                  false
              );
              context.closePath();
              context.fill();
          }
      } else if (this.orientation === 'horizontal') {
          context.lineWidth = h / 3;
          gradient = context.createLinearGradient(
              0,
              0,
              0,
              context.lineWidth
          );
          gradient.addColorStop(0, 'white');
          gradient.addColorStop(1, this.color.toString());
  
          context.strokeStyle = gradient;
          context.beginPath();
          context.moveTo(h / 2, context.lineWidth * 0.5);
          context.lineTo(w - h / 2, context.lineWidth * 0.5);
          context.stroke();
  
          gradient = context.createLinearGradient(
              0,
              h - context.lineWidth,
              0,
              h
          );
          gradient.addColorStop(0, this.color.toString());
          gradient.addColorStop(1, 'black');
  
          context.strokeStyle = gradient;
          context.beginPath();
          context.moveTo(h / 2, h - context.lineWidth * 0.5);
          context.lineTo(w - h / 2, h - context.lineWidth * 0.5);
          context.stroke();
  
          if (this.hasMiddleDip) {
              gradient = context.createLinearGradient(
                  0,
                  context.lineWidth,
                  0,
                  h - context.lineWidth
              );
  
              radius = h / 4;
              gradient.addColorStop(0, 'black');
              gradient.addColorStop(0.35, this.color.toString());
              gradient.addColorStop(0.65, this.color.toString());
              gradient.addColorStop(1, 'white');
  
              context.fillStyle = gradient;
              context.beginPath();
              context.arc(
                  this.width() / 2,
                  this.height() / 2,
                  radius,
                  radians(0),
                  radians(360),
                  false
              );
              context.closePath();
              context.fill();
          }
      }
  };
  
  //SliderButtonMorph events:
  
  SliderButtonMorph.prototype.mouseEnter = function () {
      this.image = this.highlightImage;
      this.changed();
  };
  
  SliderButtonMorph.prototype.mouseLeave = function () {
      this.image = this.normalImage;
      this.changed();
  };
  
  SliderButtonMorph.prototype.mouseDownLeft = function (pos) {
      this.image = this.pressImage;
      this.changed();
      this.escalateEvent('mouseDownLeft', pos);
  };
  
  SliderButtonMorph.prototype.mouseClickLeft = function () {
      this.image = this.highlightImage;
      this.changed();
  };
  
  SliderButtonMorph.prototype.mouseMove = function () {
      // prevent my parent from getting picked up
      nop();
  };
  
  // SliderMorph ///////////////////////////////////////////////////
  
  // SliderMorph inherits from CircleBoxMorph:
  
  SliderMorph.prototype = new CircleBoxMorph();
  SliderMorph.prototype.constructor = SliderMorph;
  SliderMorph.uber = CircleBoxMorph.prototype;
  
  function SliderMorph(start, stop, value, size, orientation, color) {
      this.init(
          start || 1,
          stop || 100,
          value || 50,
          size || 10,
          orientation || 'vertical',
          color
      );
  }
  
  SliderMorph.prototype.init = function (
      start,
      stop,
      value,
      size,
      orientation,
      color
  ) {
      this.target = null;
      this.action = null;
      this.start = start;
      this.stop = stop;
      this.value = value;
      this.size = size;
      this.offset = null;
      this.button = new SliderButtonMorph();
      this.button.isDraggable = false;
      this.button.color = new Color(200, 200, 200);
      this.button.highlightColor = new Color(210, 210, 255);
      this.button.pressColor = new Color(180, 180, 255);
      SliderMorph.uber.init.call(this, orientation);
      this.add(this.button);
      this.alpha = 0.3;
      this.color = color || new Color(0, 0, 0);
      this.setExtent(new Point(20, 100));
      // this.drawNew();
  };
  
  SliderMorph.prototype.autoOrientation = nop;
  
  SliderMorph.prototype.rangeSize = function () {
      return this.stop - this.start;
  };
  
  SliderMorph.prototype.ratio = function () {
      return this.size / (this.rangeSize() + 1);
  };
  
  SliderMorph.prototype.unitSize = function () {
      if (this.orientation === 'vertical') {
          return (this.height() - this.button.height()) /
              this.rangeSize();
      }
      return (this.width() - this.button.width()) /
          this.rangeSize();
  };
  
  SliderMorph.prototype.drawNew = function () {
      var bw, bh, posX, posY;
  
      SliderMorph.uber.drawNew.call(this);
      this.button.orientation = this.orientation;
      if (this.orientation === 'vertical') {
          bw  = this.width() - 2;
          bh = Math.max(bw, Math.round(this.height() * this.ratio()));
          this.button.silentSetExtent(new Point(bw, bh));
          posX = 1;
          posY = Math.min(
              Math.round((this.value - this.start) * this.unitSize()),
              this.height() - this.button.height()
          );
      } else {
          bh = this.height() - 2;
          bw  = Math.max(bh, Math.round(this.width() * this.ratio()));
          this.button.silentSetExtent(new Point(bw, bh));
          posY = 1;
          posX = Math.min(
              Math.round((this.value - this.start) * this.unitSize()),
              this.width() - this.button.width()
          );
      }
      this.button.setPosition(
          new Point(posX, posY).add(this.bounds.origin)
      );
      this.button.drawNew();
      this.button.changed();
  };
  
  SliderMorph.prototype.updateValue = function () {
      var relPos;
      if (this.orientation === 'vertical') {
          relPos = this.button.top() - this.top();
      } else {
          relPos = this.button.left() - this.left();
      }
      this.value = Math.round(relPos / this.unitSize() + this.start);
      this.updateTarget();
  };
  
  SliderMorph.prototype.updateTarget = function () {
      if (this.action) {
          if (typeof this.action === 'function') {
              this.action.call(this.target, this.value);
          } else { // assume it's a String
              this.target[this.action](this.value);
          }
      }
  };
  
  // SliderMorph menu:
  
  SliderMorph.prototype.developersMenu = function () {
      var menu = SliderMorph.uber.developersMenu.call(this);
      menu.addItem(
          "show value...",
          'showValue',
          'display a dialog box\nshowing the selected number'
      );
      menu.addItem(
          "floor...",
          function () {
              this.prompt(
                  menu.title + '\nfloor:',
                  this.setStart,
                  this,
                  this.start.toString(),
                  null,
                  0,
                  this.stop - this.size,
                  true
              );
          },
          'set the minimum value\nwhich can be selected'
      );
      menu.addItem(
          "ceiling...",
          function () {
              this.prompt(
                  menu.title + '\nceiling:',
                  this.setStop,
                  this,
                  this.stop.toString(),
                  null,
                  this.start + this.size,
                  this.size * 100,
                  true
              );
          },
          'set the maximum value\nwhich can be selected'
      );
      menu.addItem(
          "button size...",
          function () {
              this.prompt(
                  menu.title + '\nbutton size:',
                  this.setSize,
                  this,
                  this.size.toString(),
                  null,
                  1,
                  this.stop - this.start,
                  true
              );
          },
          'set the range\ncovered by\nthe slider button'
      );
      menu.addLine();
      menu.addItem(
          'set target',
          "setTarget",
          'select another morph\nwhose numerical property\nwill be ' +
              'controlled by this one'
      );
      return menu;
  };
  
  SliderMorph.prototype.showValue = function () {
      this.inform(this.value);
  };
  
  SliderMorph.prototype.userSetStart = function (num) {
      // for context menu demo purposes
      this.start = Math.max(num, this.stop);
  };
  
  SliderMorph.prototype.setStart = function (num, noUpdate) {
      // for context menu demo purposes
      var newStart;
      if (typeof num === 'number') {
          this.start = Math.min(
              num,
              this.stop - this.size
          );
      } else {
          newStart = parseFloat(num);
          if (!isNaN(newStart)) {
              this.start = Math.min(
                  newStart,
                  this.stop - this.size
              );
          }
      }
      this.value = Math.max(this.value, this.start);
      if (!noUpdate) {this.updateTarget(); }
      this.drawNew();
      this.changed();
  };
  
  SliderMorph.prototype.setStop = function (num, noUpdate) {
      // for context menu demo purposes
      var newStop;
      if (typeof num === 'number') {
          this.stop = Math.max(num, this.start + this.size);
      } else {
          newStop = parseFloat(num);
          if (!isNaN(newStop)) {
              this.stop = Math.max(newStop, this.start + this.size);
          }
      }
      this.value = Math.min(this.value, this.stop);
      if (!noUpdate) {this.updateTarget(); }
      this.drawNew();
      this.changed();
  };
  
  SliderMorph.prototype.setSize = function (num, noUpdate) {
      // for context menu demo purposes
      var newSize;
      if (typeof num === 'number') {
          this.size = Math.min(
              Math.max(num, 1),
              this.stop - this.start
          );
      } else {
          newSize = parseFloat(num);
          if (!isNaN(newSize)) {
              this.size = Math.min(
                  Math.max(newSize, 1),
                  this.stop - this.start
              );
          }
      }
      this.value = Math.min(this.value, this.stop - this.size);
      if (!noUpdate) {this.updateTarget(); }
      this.drawNew();
      this.changed();
  };
  
  SliderMorph.prototype.setTarget = function () {
      var choices = this.overlappedMorphs(),
          menu = new MenuMorph(this, 'choose target:'),
          myself = this;
  
      choices.push(this.world());
      choices.forEach(function (each) {
          menu.addItem(each.toString().slice(0, 50), function () {
              myself.target = each;
              myself.setTargetSetter();
          });
      });
      if (choices.length === 1) {
          this.target = choices[0];
          this.setTargetSetter();
      } else if (choices.length > 0) {
          menu.popUpAtHand(this.world());
      }
  };
  
  SliderMorph.prototype.setTargetSetter = function () {
      var choices = this.target.numericalSetters(),
          menu = new MenuMorph(this, 'choose target property:'),
          myself = this;
  
      choices.forEach(function (each) {
          menu.addItem(each, function () {
              myself.action = each;
          });
      });
      if (choices.length === 1) {
          this.action = choices[0];
      } else if (choices.length > 0) {
          menu.popUpAtHand(this.world());
      }
  };
  
  SliderMorph.prototype.numericalSetters = function () {
      // for context menu demo purposes
      var list = SliderMorph.uber.numericalSetters.call(this);
      list.push('setStart', 'setStop', 'setSize');
      return list;
  };
  
  // SliderMorph stepping:
  
  SliderMorph.prototype.step = null;
  
  SliderMorph.prototype.mouseDownLeft = function (pos) {
      var world, myself = this;
  
      if (!this.button.bounds.containsPoint(pos)) {
          this.offset = new Point(); // return null;
      } else {
          this.offset = pos.subtract(this.button.bounds.origin);
      }
      world = this.root();
      this.step = function () {
          var mousePos, newX, newY;
          if (world.hand.mouseButton) {
              mousePos = world.hand.bounds.origin;
              if (myself.orientation === 'vertical') {
                  newX = myself.button.bounds.origin.x;
                  newY = Math.max(
                      Math.min(
                          mousePos.y - myself.offset.y,
                          myself.bottom() - myself.button.height()
                      ),
                      myself.top()
                  );
              } else {
                  newY = myself.button.bounds.origin.y;
                  newX = Math.max(
                      Math.min(
                          mousePos.x - myself.offset.x,
                          myself.right() - myself.button.width()
                      ),
                      myself.left()
                  );
              }
              myself.button.setPosition(new Point(newX, newY));
              myself.updateValue();
          } else {
              this.step = null;
          }
      };
  };
  
  // MouseSensorMorph ////////////////////////////////////////////////////
  
  // for demo and debuggin purposes only, to be removed later
  
  var MouseSensorMorph;
  
  // MouseSensorMorph inherits from BoxMorph:
  
  MouseSensorMorph.prototype = new BoxMorph();
  MouseSensorMorph.prototype.constructor = MouseSensorMorph;
  MouseSensorMorph.uber = BoxMorph.prototype;
  
  // MouseSensorMorph instance creation:
  
  function MouseSensorMorph(edge, border, borderColor) {
      this.init(edge, border, borderColor);
  }
  
  MouseSensorMorph.prototype.init = function (edge, border, borderColor) {
      MouseSensorMorph.uber.init.call(this);
      this.edge = edge || 4;
      this.border = border || 2;
      this.color = new Color(255, 255, 255);
      this.borderColor = borderColor || new Color();
      this.isTouched = false;
      this.upStep = 0.05;
      this.downStep = 0.02;
      this.noticesTransparentClick = false;
      this.drawNew();
  };
  
  MouseSensorMorph.prototype.touch = function () {
      var myself = this;
      if (!this.isTouched) {
          this.isTouched = true;
          this.alpha = 0.6;
  
          this.step = function () {
              if (myself.isTouched) {
                  if (myself.alpha < 1) {
                      myself.alpha = myself.alpha + myself.upStep;
                  }
              } else if (myself.alpha > (myself.downStep)) {
                  myself.alpha = myself.alpha - myself.downStep;
              } else {
                  myself.alpha = 0;
                  myself.step = null;
              }
              myself.changed();
          };
      }
  };
  
  MouseSensorMorph.prototype.unTouch = function () {
      this.isTouched = false;
  };
  
  MouseSensorMorph.prototype.mouseEnter = function () {
      this.touch();
  };
  
  MouseSensorMorph.prototype.mouseLeave = function () {
      this.unTouch();
  };
  
  MouseSensorMorph.prototype.mouseDownLeft = function () {
      this.touch();
  };
  
  MouseSensorMorph.prototype.mouseClickLeft = function () {
      this.unTouch();
  };
  
  // InspectorMorph //////////////////////////////////////////////////////
  
  // InspectorMorph: referenced constructors
  
  var ListMorph;
  var TriggerMorph;
  
  // InspectorMorph inherits from BoxMorph:
  
  InspectorMorph.prototype = new BoxMorph();
  InspectorMorph.prototype.constructor = InspectorMorph;
  InspectorMorph.uber = BoxMorph.prototype;
  
  // InspectorMorph instance creation:
  
  function InspectorMorph(target) {
      this.init(target);
  }
  
  InspectorMorph.prototype.init = function (target) {
      // additional properties:
      this.target = target;
      this.currentProperty = null;
      this.showing = 'attributes';
      this.markOwnProperties = false;
      this.hasUserEditedDetails = false;
  
      // initialize inherited properties:
      InspectorMorph.uber.init.call(this);
  
      // override inherited properties:
      this.silentSetExtent(
          new Point(
              MorphicPreferences.handleSize * 20,
              MorphicPreferences.handleSize * 20 * 2 / 3
          )
      );
      this.isDraggable = true;
      this.border = 1;
      this.edge = MorphicPreferences.isFlat ? 1 : 5;
      this.color = new Color(60, 60, 60);
      this.borderColor = new Color(95, 95, 95);
      this.fps = 25;
      this.drawNew();
  
      // panes:
      this.label = null;
      this.list = null;
      this.detail = null;
      this.work = null;
      this.buttonInspect = null;
      this.buttonClose = null;
      this.buttonSubset = null;
      this.buttonEdit = null;
      this.resizer = null;
  
      if (this.target) {
          this.buildPanes();
      }
  };
  
  InspectorMorph.prototype.setTarget = function (target) {
      this.target = target;
      this.currentProperty = null;
      this.buildPanes();
  };
  
  InspectorMorph.prototype.updateCurrentSelection = function () {
      var val, txt, cnts,
          sel = this.list.selected,
          currentTxt = this.detail.contents.children[0],
          root = this.root();
  
      if (root &&
              (root.keyboardReceiver instanceof CursorMorph) &&
              (root.keyboardReceiver.target === currentTxt)) {
          this.hasUserEditedDetails = true;
          return;
      }
      if (isNil(sel) || this.hasUserEditedDetails) {return; }
      val = this.target[sel];
      this.currentProperty = val;
      if (isNil(val)) {
          txt = 'NULL';
      } else if (isString(val)) {
          txt = val;
      } else {
          txt = val.toString();
      }
      if (currentTxt.text === txt) {return; }
      cnts = new TextMorph(txt);
      cnts.isEditable = true;
      cnts.enableSelecting();
      cnts.setReceiver(this.target);
      this.detail.setContents(cnts);
  };
  
  InspectorMorph.prototype.buildPanes = function () {
      var attribs = [], property, myself = this, ctrl, ev, doubleClickAction;
  
      // remove existing panes
      this.children.forEach(function (m) {
          if (m !== this.work) { // keep work pane around
              m.destroy();
          }
      });
      this.children = [];
  
      // label
      this.label = new TextMorph(this.target.toString());
      this.label.fontSize = MorphicPreferences.menuFontSize;
      this.label.isBold = true;
      this.label.color = new Color(255, 255, 255);
      this.label.drawNew();
      this.add(this.label);
  
      // properties list
      for (property in this.target) {
          if (property) { // dummy condition, to be refined
              attribs.push(property);
          }
      }
      if (this.showing === 'attributes') {
          attribs = attribs.filter(function (prop) {
              return typeof myself.target[prop] !== 'function';
          });
      } else if (this.showing === 'methods') {
          attribs = attribs.filter(function (prop) {
              return typeof myself.target[prop] === 'function';
          });
      } // otherwise show all properties
  
      doubleClickAction = function () {
          var world, inspector;
          if (!isObject(myself.currentProperty)) {return; }
          world = myself.world();
          inspector = new InspectorMorph(
              myself.currentProperty
          );
          inspector.setPosition(world.hand.position());
          inspector.keepWithin(world);
          world.add(inspector);
          inspector.changed();
      };
  
      this.list = new ListMorph(
          this.target instanceof Array ? attribs : attribs.sort(),
          null, // label getter
          this.markOwnProperties ?
                  [ // format list
                      [ // format element: [color, predicate(element]
                          new Color(0, 0, 180),
                          function (element) {
                              return Object.prototype.hasOwnProperty.call(
                                  myself.target,
                                  element
                              );
                          }
                      ]
                  ]
                  : null,
          doubleClickAction
      );
  
      this.list.action = function () {
          myself.hasUserEditedDetails = false;
          myself.updateCurrentSelection();
      };
  
      this.list.hBar.alpha = 0.6;
      this.list.vBar.alpha = 0.6;
      this.list.contents.step = null;
      this.add(this.list);
  
      // details pane
      this.detail = new ScrollFrameMorph();
      this.detail.acceptsDrops = false;
      this.detail.contents.acceptsDrops = false;
      this.detail.isTextLineWrapping = true;
      this.detail.color = new Color(255, 255, 255);
      this.detail.hBar.alpha = 0.6;
      this.detail.vBar.alpha = 0.6;
      ctrl = new TextMorph('');
      ctrl.isEditable = true;
      ctrl.enableSelecting();
      ctrl.setReceiver(this.target);
      this.detail.setContents(ctrl);
      this.add(this.detail);
  
      // work ('evaluation') pane
      // don't refresh the work pane if it already exists
      if (this.work === null) {
          this.work = new ScrollFrameMorph();
          this.work.acceptsDrops = false;
          this.work.contents.acceptsDrops = false;
          this.work.isTextLineWrapping = true;
          this.work.color = new Color(255, 255, 255);
          this.work.hBar.alpha = 0.6;
          this.work.vBar.alpha = 0.6;
          ev = new TextMorph('');
          ev.isEditable = true;
          ev.enableSelecting();
          ev.setReceiver(this.target);
          this.work.setContents(ev);
      }
      this.add(this.work);
  
      // properties button
      this.buttonSubset = new TriggerMorph();
      this.buttonSubset.labelString = 'show...';
      this.buttonSubset.action = function () {
          var menu;
          menu = new MenuMorph();
          menu.addItem(
              'attributes',
              function () {
                  myself.showing = 'attributes';
                  myself.buildPanes();
              }
          );
          menu.addItem(
              'methods',
              function () {
                  myself.showing = 'methods';
                  myself.buildPanes();
              }
          );
          menu.addItem(
              'all',
              function () {
                  myself.showing = 'all';
                  myself.buildPanes();
              }
          );
          menu.addLine();
          menu.addItem(
              (myself.markOwnProperties ?
                      'un-mark own' : 'mark own'),
              function () {
                  myself.markOwnProperties = !myself.markOwnProperties;
                  myself.buildPanes();
              },
              'highlight\n\'own\' properties'
          );
          menu.popUpAtHand(myself.world());
      };
      this.add(this.buttonSubset);
  
      // inspect button
      this.buttonInspect = new TriggerMorph();
      this.buttonInspect.labelString = 'inspect...';
      this.buttonInspect.action = function () {
          var menu, world, inspector;
          if (isObject(myself.currentProperty)) {
              menu = new MenuMorph();
              menu.addItem(
                  'in new inspector...',
                  function () {
                      world = myself.world();
                      inspector = new InspectorMorph(
                          myself.currentProperty
                      );
                      inspector.setPosition(world.hand.position());
                      inspector.keepWithin(world);
                      world.add(inspector);
                      inspector.changed();
                  }
              );
              menu.addItem(
                  'here...',
                  function () {
                      myself.setTarget(myself.currentProperty);
                  }
              );
              menu.popUpAtHand(myself.world());
          } else {
              myself.inform(
                  (myself.currentProperty === null ?
                          'null' : typeof myself.currentProperty) +
                              '\nis not inspectable'
              );
          }
      };
      this.add(this.buttonInspect);
  
      // edit button
  
      this.buttonEdit = new TriggerMorph();
      this.buttonEdit.labelString = 'edit...';
      this.buttonEdit.action = function () {
          var menu;
          menu = new MenuMorph(myself);
          menu.addItem("save", 'save', 'accept changes');
          menu.addLine();
          menu.addItem("add property...", 'addProperty');
          menu.addItem("rename...", 'renameProperty');
          menu.addItem("remove...", 'removeProperty');
          menu.popUpAtHand(myself.world());
      };
      this.add(this.buttonEdit);
  
      // close button
      this.buttonClose = new TriggerMorph();
      this.buttonClose.labelString = 'close';
      this.buttonClose.action = function () {
          myself.destroy();
      };
      this.add(this.buttonClose);
  
      // resizer
      this.resizer = new HandleMorph(
          this,
          150,
          100,
          this.edge,
          this.edge
      );
  
      // update layout
      this.fixLayout();
  };
  
  InspectorMorph.prototype.fixLayout = function () {
      var x, y, r, b, w, h;
  
      Morph.prototype.trackChanges = false;
  
      // label
      x = this.left() + this.edge;
      y = this.top() + this.edge;
      r = this.right() - this.edge;
      w = r - x;
      this.label.setPosition(new Point(x, y));
      this.label.setWidth(w);
      if (this.label.height() > (this.height() - 50)) {
          this.silentSetHeight(this.label.height() + 50);
          this.drawNew();
          this.changed();
          this.resizer.drawNew();
      }
  
      // list
      y = this.label.bottom() + 2;
      w = Math.min(
          Math.floor(this.width() / 3),
          this.list.listContents.width()
      );
  
      w -= this.edge;
      b = this.bottom() - (2 * this.edge) -
          MorphicPreferences.handleSize;
      h = b - y;
      this.list.setPosition(new Point(x, y));
      this.list.setExtent(new Point(w, h));
  
      // detail
      x = this.list.right() + this.edge;
      r = this.right() - this.edge;
      w = r - x;
      this.detail.setPosition(new Point(x, y));
      this.detail.setExtent(new Point(w, (h * 2 / 3) - this.edge));
  
      // work
      y = this.detail.bottom() + this.edge;
      this.work.setPosition(new Point(x, y));
      this.work.setExtent(new Point(w, h / 3));
  
      // properties button
      x = this.list.left();
      y = this.list.bottom() + this.edge;
      w = this.list.width();
      h = MorphicPreferences.handleSize;
      this.buttonSubset.setPosition(new Point(x, y));
      this.buttonSubset.setExtent(new Point(w, h));
  
      // inspect button
      x = this.detail.left();
      w = this.detail.width() - this.edge -
          MorphicPreferences.handleSize;
      w = w / 3 - this.edge / 3;
      this.buttonInspect.setPosition(new Point(x, y));
      this.buttonInspect.setExtent(new Point(w, h));
  
      // edit button
      x = this.buttonInspect.right() + this.edge;
      this.buttonEdit.setPosition(new Point(x, y));
      this.buttonEdit.setExtent(new Point(w, h));
  
      // close button
      x = this.buttonEdit.right() + this.edge;
      r = this.detail.right() - this.edge -
          MorphicPreferences.handleSize;
      w = r - x;
      this.buttonClose.setPosition(new Point(x, y));
      this.buttonClose.setExtent(new Point(w, h));
  
      Morph.prototype.trackChanges = true;
      this.changed();
  
  };
  
  InspectorMorph.prototype.setExtent = function (aPoint) {
      InspectorMorph.uber.setExtent.call(this, aPoint);
      this.fixLayout();
  };
  
  // InspectorMorph editing ops:
  
  InspectorMorph.prototype.save = function () {
      var txt = this.detail.contents.children[0].text.toString(),
          prop = this.list.selected;
      try {
          // this.target[prop] = evaluate(txt);
          this.target.evaluateString('this.' + prop + ' = ' + txt);
          this.hasUserEditedDetails = false;
          if (this.target.drawNew) {
              this.target.changed();
              this.target.drawNew();
              this.target.changed();
          }
      } catch (err) {
          this.inform(err);
      }
  };
  
  InspectorMorph.prototype.addProperty = function () {
      var myself = this;
      this.prompt(
          'new property name:',
          function (prop) {
              if (prop) {
                  myself.target[prop] = null;
                  myself.buildPanes();
                  if (myself.target.drawNew) {
                      myself.target.changed();
                      myself.target.drawNew();
                      myself.target.changed();
                  }
              }
          },
          this,
          'property' // Chrome cannot handle empty strings (others do)
      );
  };
  
  InspectorMorph.prototype.renameProperty = function () {
      var myself = this,
          propertyName = this.list.selected;
      this.prompt(
          'property name:',
          function (prop) {
              try {
                  delete (myself.target[propertyName]);
                  myself.target[prop] = myself.currentProperty;
              } catch (err) {
                  myself.inform(err);
              }
              myself.buildPanes();
              if (myself.target.drawNew) {
                  myself.target.changed();
                  myself.target.drawNew();
                  myself.target.changed();
              }
          },
          this,
          propertyName
      );
  };
  
  InspectorMorph.prototype.removeProperty = function () {
      var prop = this.list.selected;
      try {
          delete (this.target[prop]);
          this.currentProperty = null;
          this.buildPanes();
          if (this.target.drawNew) {
              this.target.changed();
              this.target.drawNew();
              this.target.changed();
          }
      } catch (err) {
          this.inform(err);
      }
  };
  
  // InspectorMorph stepping
  
  InspectorMorph.prototype.step = function () {
      this.updateCurrentSelection();
      var lbl = this.target.toString();
      if (this.label.text === lbl) {return; }
      this.label.text = lbl;
      this.label.drawNew();
      this.fixLayout();
  };
  
  // InspectorMorph duplicating:
  
  InspectorMorph.prototype.updateReferences = function (map) {
      var active = this.list.activeIndex();
      InspectorMorph.uber.updateReferences.call(this, map);
      this.buildPanes();
      this.list.activateIndex(active);
  };
  
  // MenuMorph ///////////////////////////////////////////////////////////
  
  // MenuMorph: referenced constructors
  
  var MenuItemMorph;
  
  // MenuMorph inherits from BoxMorph:
  
  MenuMorph.prototype = new BoxMorph();
  MenuMorph.prototype.constructor = MenuMorph;
  MenuMorph.uber = BoxMorph.prototype;
  
  // MenuMorph instance creation:
  
  function MenuMorph(target, title, environment, fontSize) {
      this.init(target, title, environment, fontSize);
  
      /*
      if target is a function, use it as callback:
      execute target as callback function with the action property
      of the triggered MenuItem as argument.
      Use the environment, if it is specified.
      Note: if action is also a function, instead of becoming
      the argument itself it will be called to answer the argument.
      For selections, Yes/No Choices etc.
  
      else (if target is not a function):
  
          if action is a function:
          execute the action with target as environment (can be null)
          for lambdafied (inline) actions
  
          else if action is a String:
          treat it as function property of target and execute it
          for selector-like actions
      */
  }
  
  MenuMorph.prototype.init = function (target, title, environment, fontSize) {
      // additional properties:
      this.target = target;
      this.title = title || null;
      this.environment = environment || null;
      this.fontSize = fontSize || null;
      this.items = [];
      this.label = null;
      this.world = null;
      this.isListContents = false;
      this.hasFocus = false;
      this.selection = null;
      this.submenu = null;
  
      // initialize inherited properties:
      MenuMorph.uber.init.call(this);
  
      // override inherited properties:
      this.isDraggable = false;
  
      // immutable properties:
      this.border = null;
      this.edge = null;
  };
  
  MenuMorph.prototype.addItem = function (
      labelString,
      action,
      hint,
      color,
      bold, // bool
      italic, // bool
      doubleClickAction, // optional, when used as list contents
      shortcut // optional string, icon (Morph or Canvas) or tuple [icon, string]
  ) {
      /*
      labelString is normally a single-line string. But it can also be one
      of the following:
  
          * a multi-line string (containing line breaks)
          * an icon (either a Morph or a Canvas)
          * a tuple of format: [icon, string]
      */
      this.items.push([
          localize(labelString || 'close'),
          action || nop,
          hint,
          color,
          bold || false,
          italic || false,
          doubleClickAction,
          shortcut]);
  };
  
  MenuMorph.prototype.addMenu = function (label, aMenu, indicator) {
      this.addPair(label, aMenu, isNil(indicator) ? '\u25ba' : indicator);
  };
  
  MenuMorph.prototype.addPair = function (label, action, shortcut, hint) {
      this.addItem(label, action, hint, null, null, null, null, shortcut);
  };
  
  MenuMorph.prototype.addLine = function (width) {
      this.items.push([0, width || 1]);
  };
  
  MenuMorph.prototype.createLabel = function () {
      var text;
      if (this.label !== null) {
          this.label.destroy();
      }
      text = new TextMorph(
          localize(this.title),
          this.fontSize || MorphicPreferences.menuFontSize,
          MorphicPreferences.menuFontName,
          true,
          false,
          'center'
      );
      text.alignment = 'center';
      text.color = new Color(255, 255, 255);
      text.backgroundColor = this.borderColor;
      text.drawNew();
      this.label = new BoxMorph(3, 0);
      if (MorphicPreferences.isFlat) {
          this.label.edge = 0;
      }
      this.label.color = this.borderColor;
      this.label.borderColor = this.borderColor;
      this.label.setExtent(text.extent().add(4));
      this.label.drawNew();
      this.label.add(text);
      this.label.text = text;
  };
  
  MenuMorph.prototype.drawNew = function () {
      var myself = this,
          item,
          fb,
          x,
          y,
          isLine = false;
  
      this.children.forEach(function (m) {
          m.destroy();
      });
      this.children = [];
      if (!this.isListContents) {
          this.edge = MorphicPreferences.isFlat ? 0 : 5;
          this.border = MorphicPreferences.isFlat ? 1 : 2;
      }
      this.color = new Color(255, 255, 255);
      this.borderColor = new Color(60, 60, 60);
      this.silentSetExtent(new Point(0, 0));
  
      y = 2;
      x = this.left() + 4;
      if (!this.isListContents) {
          if (this.title) {
              this.createLabel();
              this.label.setPosition(this.bounds.origin.add(4));
              this.add(this.label);
              y = this.label.bottom();
          } else {
              y = this.top() + 4;
          }
      }
      y += 1;
      this.items.forEach(function (tuple) {
          isLine = false;
          if (tuple instanceof StringFieldMorph ||
                  tuple instanceof ColorPickerMorph ||
                  tuple instanceof SliderMorph) {
              item = tuple;
          } else if (tuple[0] === 0) {
              isLine = true;
              item = new Morph();
              item.color = myself.borderColor;
              item.setHeight(tuple[1]);
          } else {
              item = new MenuItemMorph(
                  myself.target,
                  tuple[1],
                  tuple[0],
                  myself.fontSize || MorphicPreferences.menuFontSize,
                  MorphicPreferences.menuFontName,
                  myself.environment,
                  tuple[2], // bubble help hint
                  tuple[3], // color
                  tuple[4], // bold
                  tuple[5], // italic
                  tuple[6], // doubleclick action
                  tuple[7] // shortcut
              );
          }
          if (isLine) {
              y += 1;
          }
          item.setPosition(new Point(x, y));
          myself.add(item);
          y = y + item.height();
          if (isLine) {
              y += 1;
          }
      });
  
      fb = this.fullBounds();
      this.silentSetExtent(fb.extent().add(4));
      this.adjustWidths();
      MenuMorph.uber.drawNew.call(this);
  };
  
  MenuMorph.prototype.maxWidth = function () {
      var w = 0;
  
      if (this.parent instanceof FrameMorph) {
          if (this.parent.scrollFrame instanceof ScrollFrameMorph) {
              w = this.parent.scrollFrame.width();
          }
      }
      this.children.forEach(function (item) {
          if (item instanceof MenuItemMorph) {
              w = Math.max(
                  w,
                  item.label.width() + 8 +
                      (item.shortcut ? item.shortcut.width() + 4 : 0)
              );
          } else if ((item instanceof StringFieldMorph) ||
                  (item instanceof ColorPickerMorph) ||
                  (item instanceof SliderMorph)) {
              w = Math.max(w, item.width());
          }
      });
      if (this.label) {
          w = Math.max(w, this.label.width());
      }
      return w;
  };
  
  MenuMorph.prototype.adjustWidths = function () {
      var w = this.maxWidth(),
          isSelected,
          myself = this;
      this.children.forEach(function (item) {
          item.silentSetWidth(w);
          if (item instanceof MenuItemMorph) {
              item.fixLayout();
              isSelected = (item.image === item.pressImage);
              item.createBackgrounds();
              if (isSelected) {
                  item.image = item.pressImage;
              }
          } else {
              item.drawNew();
              if (item === myself.label) {
                  item.text.setPosition(
                      item.center().subtract(
                          item.text.extent().floorDivideBy(2)
                      )
                  );
              }
          }
      });
  };
  
  MenuMorph.prototype.unselectAllItems = function () {
      this.children.forEach(function (item) {
          if (item instanceof MenuItemMorph) {
              item.image = item.normalImage;
          } else if (item instanceof ScrollFrameMorph) {
          	item.contents.children.forEach(function (morph) {
           		if (morph instanceof MenuItemMorph) {
             			morph.image = morph.normalImage;
                	}
           	});
          }
      });
      this.changed();
  };
  
  // MenuMorph popping up
  
  MenuMorph.prototype.popup = function (world, pos) {
  	var scroller;
  
      this.drawNew();
      this.setPosition(pos);
      this.addShadow(new Point(2, 2), 80);
      this.keepWithin(world);
  
      if (this.bottom() > world.bottom()) {
      	// scroll menu items if the menu is taller than the world
      	this.removeShadow();
          scroller = this.scroll();
          this.bounds.corner.y = world.bottom() - 2;
          MenuMorph.uber.drawNew.call(this);
          this.addShadow(new Point(2, 2), 80);
          scroller.setHeight(world.bottom() - scroller.top() - 6);
          scroller.adjustScrollBars(); // ?
       }
  
      if (world.activeMenu) {
          world.activeMenu.destroy();
      }
      if (this.items.length < 1 && !this.title) { // don't show empty menus
          return;
      }
      world.add(this);
      world.activeMenu = this;
      this.world = world; // optionally enable keyboard support
      this.fullChanged();
  };
  
  MenuMorph.prototype.scroll = function () {
      // private - move all items into a scroll frame
       var scroller = new ScrollFrameMorph(),
            start = this.label ? 1 : 0,
          first = this.children[start];
  
      scroller.setPosition(first.position());
        this.children.slice(start).forEach(function (morph) {
          scroller.addContents(morph);
      });
      this.add(scroller);
      scroller.setWidth(first.width());
      return scroller;
  };
  
  MenuMorph.prototype.popUpAtHand = function (world) {
      var wrrld = world || this.world;
      this.popup(wrrld, wrrld.hand.position());
  };
  
  MenuMorph.prototype.popUpCenteredAtHand = function (world) {
      var wrrld = world || this.world;
      this.drawNew();
      this.popup(
          wrrld,
          wrrld.hand.position().subtract(
              this.extent().floorDivideBy(2)
          )
      );
  };
  
  MenuMorph.prototype.popUpCenteredInWorld = function (world) {
      var wrrld = world || this.world;
      this.drawNew();
      this.popup(
          wrrld,
          wrrld.center().subtract(
              this.extent().floorDivideBy(2)
          )
      );
  };
  
  // MenuMorph submenus
  
  MenuMorph.prototype.closeRootMenu = function () {
      if (this.parent instanceof MenuMorph) {
          this.parent.closeRootMenu();
      } else {
          this.destroy();
      }
  };
  
  MenuMorph.prototype.closeSubmenu = function () {
      if (this.submenu) {
          this.submenu.destroy();
          this.submenu = null;
          this.unselectAllItems();
      }
  };
  
  // MenuMorph keyboard accessibility
  
  MenuMorph.prototype.getFocus = function () {
      this.world.keyboardReceiver = this;
      this.selection = null;
      this.selectFirst();
      this.hasFocus = true;
  };
  
  MenuMorph.prototype.processKeyDown = function (event) {
      // console.log(event.keyCode);
      switch (event.keyCode) {
      case 13: // 'enter'
      case 32: // 'space'
          if (this.selection) {
              this.selection.mouseClickLeft();
              if (this.submenu) {
                  this.submenu.getFocus();
              }
          }
          return;
      case 27: // 'esc'
          return this.destroy();
      case 37: // 'left arrow'
          return this.leaveSubmenu();
      case 38: // 'up arrow'
          return this.selectUp();
      case 39: // 'right arrow'
          return this.enterSubmenu();
      case 40: // 'down arrow'
          return this.selectDown();
      default:
          nop();
      }
  };
  
  MenuMorph.prototype.processKeyUp = function (event) {
      nop(event);
  };
  
  MenuMorph.prototype.processKeyPress = function (event) {
      nop(event);
  };
  
  MenuMorph.prototype.selectFirst = function () {
      var scroller, items, i;
  
      scroller = detect(this.children, function (morph) {
           return morph instanceof ScrollFrameMorph;
      });
      items = scroller ? scroller.contents.children : this.children;
      for (i = 0; i < items.length; i += 1) {
          if (items[i] instanceof MenuItemMorph) {
              this.select(items[i]);
              return;
      	}
  	}
  };
  
  MenuMorph.prototype.selectUp = function () {
      var scroller, triggers, idx;
  
  	scroller = detect(this.children, function (morph) {
   		return morph instanceof ScrollFrameMorph;
      });
      triggers = (scroller ? scroller.contents.children : this.children).filter(
      	function (each) {
          	return each instanceof MenuItemMorph;
      	}
      );
      if (!this.selection) {
          if (triggers.length) {
              this.select(triggers[0]);
          }
          return;
      }
      idx = triggers.indexOf(this.selection) - 1;
      if (idx < 0) {
          idx = triggers.length - 1;
      }
      this.select(triggers[idx]);
  };
  
  MenuMorph.prototype.selectDown = function () {
      var scroller, triggers, idx;
  
      scroller = detect(this.children, function (morph) {
           return morph instanceof ScrollFrameMorph;
      });
      triggers = (scroller ? scroller.contents.children : this.children).filter(
          function (each) {
              return each instanceof MenuItemMorph;
          }
      );
      if (!this.selection) {
          if (triggers.length) {
              this.select(triggers[0]);
          }
          return;
      }
      idx = triggers.indexOf(this.selection) + 1;
      if (idx >= triggers.length) {
          idx = 0;
      }
      this.select(triggers[idx]);
  };
  
  MenuMorph.prototype.enterSubmenu = function () {
      if (this.selection && this.selection.action instanceof MenuMorph) {
          this.selection.popUpSubmenu();
          if (this.submenu) {
              this.submenu.getFocus();
          }
      }
  };
  
  MenuMorph.prototype.leaveSubmenu = function () {
      var menu = this.parent;
      if (this.parent instanceof MenuMorph) {
          menu.submenu = null;
          menu.hasFocus = true;
          this.destroy();
          menu.world.keyboardReceiver = menu;
      }
  };
  
  MenuMorph.prototype.select = function (aMenuItem) {
      this.unselectAllItems();
      aMenuItem.image = aMenuItem.highlightImage;
      aMenuItem.changed();
      aMenuItem.scrollIntoView();
      this.selection = aMenuItem;
  };
  
  MenuMorph.prototype.destroy = function () {
      if (this.hasFocus) {
          this.world.keyboardReceiver = null;
      }
      MenuMorph.uber.destroy.call(this);
  };
  
  // StringMorph /////////////////////////////////////////////////////////
  
  // I am a single line of text
  
  // StringMorph inherits from Morph:
  
  StringMorph.prototype = new Morph();
  StringMorph.prototype.constructor = StringMorph;
  StringMorph.uber = Morph.prototype;
  
  // StringMorph instance creation:
  
  function StringMorph(
      text,
      fontSize,
      fontStyle,
      bold,
      italic,
      isNumeric,
      shadowOffset,
      shadowColor,
      color,
      fontName
  ) {
      this.init(
          text,
          fontSize,
          fontStyle,
          bold,
          italic,
          isNumeric,
          shadowOffset,
          shadowColor,
          color,
          fontName
      );
  }
  
  StringMorph.prototype.init = function (
      text,
      fontSize,
      fontStyle,
      bold,
      italic,
      isNumeric,
      shadowOffset,
      shadowColor,
      color,
      fontName
  ) {
      // additional properties:
      this.text = text || ((text === '') ? '' : 'StringMorph');
      this.fontSize = fontSize || 12;
      this.fontName = fontName || MorphicPreferences.globalFontFamily;
      this.fontStyle = fontStyle || 'sans-serif';
      this.isBold = bold || false;
      this.isItalic = italic || false;
      this.isEditable = false;
      this.isNumeric = isNumeric || false;
      this.isPassword = false;
      this.shadowOffset = shadowOffset || new Point(0, 0);
      this.shadowColor = shadowColor || null;
      this.isShowingBlanks = false;
      this.blanksColor = new Color(180, 140, 140);
  
      // additional properties for text-editing:
      this.isScrollable = true; // scrolls into view when edited
      this.currentlySelecting = false;
      this.startMark = 0;
      this.endMark = 0;
      this.markedTextColor = new Color(255, 255, 255);
      this.markedBackgoundColor = new Color(60, 60, 120);
  
      // initialize inherited properties:
      StringMorph.uber.init.call(this, true);
  
      // override inherited properites:
      this.color = color || new Color(0, 0, 0);
      this.noticesTransparentClick = true;
      this.drawNew();
  };
  
  StringMorph.prototype.toString = function () {
      // e.g. 'a StringMorph("Hello World")'
      return 'a ' +
          (this.constructor.name ||
              this.constructor.toString().split(' ')[1].split('(')[0]) +
          '("' + this.text.slice(0, 30) + '...")';
  };
  
  StringMorph.prototype.password = function (letter, length) {
      var ans = '',
          i;
      for (i = 0; i < length; i += 1) {
          ans += letter;
      }
      return ans;
  };
  
  StringMorph.prototype.font = function () {
      // answer a font string, e.g. 'bold italic 12px sans-serif'
      var font = '';
      if (this.isBold) {
          font = font + 'bold ';
      }
      if (this.isItalic) {
          font = font + 'italic ';
      }
      return font +
          this.fontSize + 'px ' +
          (this.fontName ? this.fontName + ', ' : '') +
          this.fontStyle;
  };
  
  StringMorph.prototype.drawNew = function () {
      var context, width, start, stop, i, p, c, x, y,
          shadowOffset = this.shadowOffset || new Point(),
          txt = this.isPassword ?
                  this.password('*', this.text.length) : this.text;
  
      // initialize my surface property
      this.image = newCanvas();
      context = this.image.getContext('2d');
      context.font = this.font();
  
      // set my extent
      width = Math.max(
          context.measureText(txt).width + Math.abs(shadowOffset.x),
          1
      );
      this.bounds.corner = this.bounds.origin.add(
          new Point(
              width,
              fontHeight(this.fontSize) + Math.abs(shadowOffset.y)
          )
      );
      this.image.width = width;
      this.image.height = this.height();
  
      // prepare context for drawing text
      context.font = this.font();
      context.textAlign = 'left';
      context.textBaseline = 'bottom';
  
      // first draw the shadow, if any
      if (this.shadowColor) {
          x = Math.max(shadowOffset.x, 0);
          y = Math.max(shadowOffset.y, 0);
          context.fillStyle = this.shadowColor.toString();
          context.fillText(txt, x, fontHeight(this.fontSize) + y);
      }
  
      // now draw the actual text
      x = Math.abs(Math.min(shadowOffset.x, 0));
      y = Math.abs(Math.min(shadowOffset.y, 0));
      context.fillStyle = this.color.toString();
  
      if (this.isShowingBlanks) {
          this.renderWithBlanks(context, x, fontHeight(this.fontSize) + y);
      } else {
          context.fillText(txt, x, fontHeight(this.fontSize) + y);
      }
  
      // draw the selection
      start = Math.min(this.startMark, this.endMark);
      stop = Math.max(this.startMark, this.endMark);
      for (i = start; i < stop; i += 1) {
          p = this.slotPosition(i).subtract(this.position());
          c = txt.charAt(i);
          context.fillStyle = this.markedBackgoundColor.toString();
          context.fillRect(p.x, p.y, context.measureText(c).width + 1 + x,
              fontHeight(this.fontSize) + y);
          context.fillStyle = this.markedTextColor.toString();
          context.fillText(c, p.x + x, fontHeight(this.fontSize) + y);
      }
  
      // notify my parent of layout change
      if (this.parent) {
          if (this.parent.fixLayout) {
              this.parent.fixLayout();
          }
      }
  };
  
  StringMorph.prototype.renderWithBlanks = function (context, startX, y) {
      var space = context.measureText(' ').width,
          blank = newCanvas(new Point(space, this.height())),
          ctx = blank.getContext('2d'),
          words = this.text.split(' '),
          x = startX || 0,
          isFirst = true;
  
      // create the blank form
      ctx.fillStyle = this.blanksColor.toString();
      ctx.arc(
          space / 2,
          blank.height / 2,
          space / 2,
          radians(0),
          radians(360)
      );
      ctx.fill();
  
      function drawBlank() {
          context.drawImage(blank, x, 0);
          x += space;
      }
  
      // render my text inserting blanks
      words.forEach(function (word) {
          if (!isFirst) {
              drawBlank();
          }
          isFirst = false;
          if (word !== '') {
              context.fillText(word, x, y);
              x += context.measureText(word).width;
          }
      });
  };
  
  // StringMorph measuring:
  
  StringMorph.prototype.slotPosition = function (slot) {
      // answer the position point of the given index ("slot")
      // where the cursor should be placed
      var txt = this.isPassword ?
                  this.password('*', this.text.length) : this.text,
          dest = Math.min(Math.max(slot, 0), txt.length),
          context = this.image.getContext('2d'),
          xOffset,
          x,
          y,
          idx;
  
      xOffset = 0;
      for (idx = 0; idx < dest; idx += 1) {
          xOffset += context.measureText(txt[idx]).width;
      }
      this.pos = dest;
      x = this.left() + xOffset;
      y = this.top();
      return new Point(x, y);
  };
  
  StringMorph.prototype.slotAt = function (aPoint) {
      // answer the slot (index) closest to the given point taking
      // in account how far from the middle of the character it is,
      // so the cursor can be moved accordingly
  
      var txt = this.isPassword ?
                  this.password('*', this.text.length) : this.text,
          idx = 0,
          charX = 0,
          context = this.image.getContext('2d');
  
      while (aPoint.x - this.left() > charX) {
          charX += context.measureText(txt[idx]).width;
          idx += 1;
          if (idx === txt.length) {
              if ((context.measureText(txt).width -
                      (context.measureText(txt[idx - 1]).width / 2)) <
                      (aPoint.x - this.left())) {
                  return idx;
              }
          }
      }
  
      // see where our click fell with respect to the middle of the char
      if (aPoint.x - this.left() >
              charX - context.measureText(txt[idx - 1]).width / 2) {
          return idx;
      } else {
          return idx - 1;
      }
  };
  
  StringMorph.prototype.upFrom = function (slot) {
      // answer the slot above the given one
      return slot;
  };
  
  StringMorph.prototype.downFrom = function (slot) {
      // answer the slot below the given one
      return slot;
  };
  
  StringMorph.prototype.startOfLine = function () {
      // answer the first slot (index) of the line for the given slot
      return 0;
  };
  
  StringMorph.prototype.endOfLine = function () {
      // answer the slot (index) indicating the EOL for the given slot
      return this.text.length;
  };
  
  StringMorph.prototype.previousWordFrom = function (aSlot) {
      // answer the slot (index) slots indicating the position of the
      // previous word to the left of aSlot
      var index = aSlot - 1;
      
      // while the current character is non-word one, we skip it, so that
      // if we are in the middle of a non-alphanumeric sequence, we'll get
      // right to the beginning of the previous word
      while (index > 0 && !isWordChar(this.text[index])) {
          index -= 1;
      }
  
      // while the current character is a word one, we skip it until we
      // find the beginning of the current word
      while (index > 0 && isWordChar(this.text[index - 1])) {
          index -= 1;
      }
  
      return index;
  };
  
  StringMorph.prototype.nextWordFrom = function (aSlot) {
      var index = aSlot;
      
      while (index < this.endOfLine() && !isWordChar(this.text[index])) {
          index += 1;
      }
  
      while (index < this.endOfLine() && isWordChar(this.text[index])) {
          index += 1;
      }
  
      return index;
  };
  
  StringMorph.prototype.rawHeight = function () {
      // answer my corrected fontSize
      return this.height() / 1.2;
  };
  
  // StringMorph menus:
  
  StringMorph.prototype.developersMenu = function () {
      var menu = StringMorph.uber.developersMenu.call(this);
  
      menu.addLine();
      menu.addItem("edit", 'edit');
      menu.addItem(
          "font size...",
          function () {
              this.prompt(
                  menu.title + '\nfont\nsize:',
                  this.setFontSize,
                  this,
                  this.fontSize.toString(),
                  null,
                  6,
                  500,
                  true
              );
          },
          'set this String\'s\nfont point size'
      );
      if (this.fontStyle !== 'serif') {
          menu.addItem("serif", 'setSerif');
      }
      if (this.fontStyle !== 'sans-serif') {
          menu.addItem("sans-serif", 'setSansSerif');
      }
      if (this.isBold) {
          menu.addItem("normal weight", 'toggleWeight');
      } else {
          menu.addItem("bold", 'toggleWeight');
      }
      if (this.isItalic) {
          menu.addItem("normal style", 'toggleItalic');
      } else {
          menu.addItem("italic", 'toggleItalic');
      }
      if (this.isShowingBlanks) {
          menu.addItem("hide blanks", 'toggleShowBlanks');
      } else {
          menu.addItem("show blanks", 'toggleShowBlanks');
      }
      if (this.isPassword) {
          menu.addItem("show characters", 'toggleIsPassword');
      } else {
          menu.addItem("hide characters", 'toggleIsPassword');
      }
      return menu;
  };
  
  StringMorph.prototype.toggleIsDraggable = function () {
      // for context menu demo purposes
      this.isDraggable = !this.isDraggable;
      if (this.isDraggable) {
          this.disableSelecting();
      } else {
          this.enableSelecting();
      }
  };
  
  StringMorph.prototype.toggleShowBlanks = function () {
      this.isShowingBlanks = !this.isShowingBlanks;
      this.changed();
      this.drawNew();
      this.changed();
  };
  
  StringMorph.prototype.toggleWeight = function () {
      this.isBold = !this.isBold;
      this.changed();
      this.drawNew();
      this.changed();
  };
  
  StringMorph.prototype.toggleItalic = function () {
      this.isItalic = !this.isItalic;
      this.changed();
      this.drawNew();
      this.changed();
  };
  
  StringMorph.prototype.toggleIsPassword = function () {
      this.isPassword = !this.isPassword;
      this.changed();
      this.drawNew();
      this.changed();
  };
  
  StringMorph.prototype.setSerif = function () {
      this.fontStyle = 'serif';
      this.changed();
      this.drawNew();
      this.changed();
  };
  
  StringMorph.prototype.setSansSerif = function () {
      this.fontStyle = 'sans-serif';
      this.changed();
      this.drawNew();
      this.changed();
  };
  
  StringMorph.prototype.setFontSize = function (size) {
      // for context menu demo purposes
      var newSize;
      if (typeof size === 'number') {
          this.fontSize = Math.round(Math.min(Math.max(size, 4), 500));
      } else {
          newSize = parseFloat(size);
          if (!isNaN(newSize)) {
              this.fontSize = Math.round(
                  Math.min(Math.max(newSize, 4), 500)
              );
          }
      }
      this.changed();
      this.drawNew();
      this.changed();
  };
  
  StringMorph.prototype.setText = function (size) {
      // for context menu demo purposes
      this.text = Math.round(size).toString();
      this.changed();
      this.drawNew();
      this.changed();
  };
  
  StringMorph.prototype.numericalSetters = function () {
      // for context menu demo purposes
      return [
          'setLeft',
          'setTop',
          'setAlphaScaled',
          'setFontSize',
          'setText'
      ];
  };
  
  // StringMorph editing:
  
  StringMorph.prototype.edit = function () {
      this.root().edit(this);
  };
  
  StringMorph.prototype.selection = function () {
      var start, stop;
      start = Math.min(this.startMark, this.endMark);
      stop = Math.max(this.startMark, this.endMark);
      return this.text.slice(start, stop);
  };
  
  StringMorph.prototype.selectionStartSlot = function () {
      return Math.min(this.startMark, this.endMark);
  };
  
  StringMorph.prototype.clearSelection = function () {
      if (!this.currentlySelecting &&
              isNil(this.startMark) &&
              isNil(this.endMark)) {
          return;
      }
      this.currentlySelecting = false;
      this.startMark = null;
      this.endMark = null;
      this.drawNew();
      this.changed();
  };
  
  StringMorph.prototype.deleteSelection = function () {
      var start, stop, text;
      text = this.text;
      start = Math.min(this.startMark, this.endMark);
      stop = Math.max(this.startMark, this.endMark);
      this.text = text.slice(0, start) + text.slice(stop);
      this.changed();
      this.clearSelection();
  };
  
  StringMorph.prototype.selectAll = function () {
      var cursor;
      if (this.isEditable) {
          this.startMark = 0;
          cursor = this.root().cursor;
          if (cursor) {
              cursor.gotoSlot(this.text.length);
          }
          this.endMark = this.text.length;
          this.drawNew();
          this.changed();
      }
  };
  
  StringMorph.prototype.mouseDownLeft = function (pos) {
      if (this.world().currentKey === 16) {
          this.shiftClick(pos);
      } else if (this.isEditable) {
          this.clearSelection();
      } else {
          this.escalateEvent('mouseDownLeft', pos);
      }
  };
  
  StringMorph.prototype.shiftClick = function (pos) {
      var cursor = this.root().cursor;
  
      if (cursor) {
          if (!this.startMark) {
              this.startMark = cursor.slot;
          }
          cursor.gotoPos(pos);
          this.endMark = cursor.slot;
          this.drawNew();
          this.changed();
      }
      this.currentlySelecting = false;
      this.escalateEvent('mouseDownLeft', pos);
  };
  
  StringMorph.prototype.mouseClickLeft = function (pos) {
      var cursor;
      if (this.isEditable) {
          if (!this.currentlySelecting) {
              this.edit(); // creates a new cursor
          }
          cursor = this.root().cursor;
          if (cursor) {
              cursor.gotoPos(pos);
          }
          this.currentlySelecting = true;
      } else {
          this.escalateEvent('mouseClickLeft', pos);
      }
  };
  
  StringMorph.prototype.mouseDoubleClick = function (pos) {
      // selects the word at pos
      // if there is no word, we select whatever is between
      // the previous and next words
      var slot = this.slotAt(pos);
  
      if (this.isEditable) {
          this.edit();
  
          if (slot === this.text.length) {
              slot -= 1;
          }
  
          if (this.text[slot] && isWordChar(this.text[slot])) {
              this.selectWordAt(slot);
          } else if (this.text[slot]) {
              this.selectBetweenWordsAt(slot);
          } else {
              // special case for when we click right after the
              // last slot in multi line TextMorphs
              this.selectAll();
          }
      } else {
          this.escalateEvent('mouseDoubleClick', pos);
      }
  };
  
  StringMorph.prototype.selectWordAt = function (slot) {
      var cursor = this.root().cursor;
  
      if (slot === 0 || isWordChar(this.text[slot - 1])) {
          cursor.gotoSlot(this.previousWordFrom(slot));
          this.startMark = cursor.slot;
          this.endMark = this.nextWordFrom(cursor.slot);
      } else {
          cursor.gotoSlot(slot);
          this.startMark = slot;
          this.endMark = this.nextWordFrom(slot);
      }
  
      this.drawNew();
      this.changed();
  };
  
  StringMorph.prototype.selectBetweenWordsAt = function (slot) {
      var cursor = this.root().cursor;
  
      cursor.gotoSlot(this.nextWordFrom(this.previousWordFrom(slot)));
      this.startMark = cursor.slot;
      this.endMark = cursor.slot;
  
      while (this.endMark < this.text.length
              && !isWordChar(this.text[this.endMark])) {
          this.endMark += 1;
      }
  
      this.drawNew();
      this.changed();
  };
  
  StringMorph.prototype.enableSelecting = function () {
      this.mouseDownLeft = function (pos) {
          var crs = this.root().cursor,
              already = crs ? crs.target === this : false;
          if (this.world().currentKey === 16) {
              this.shiftClick(pos);
          } else {
              this.clearSelection();
              if (this.isEditable && (!this.isDraggable)) {
                  this.edit();
                  this.root().cursor.gotoPos(pos);
                  this.startMark = this.slotAt(pos);
                  this.endMark = this.startMark;
                  this.currentlySelecting = true;
                  if (!already) {this.escalateEvent('mouseDownLeft', pos); }
              }
          }
      };
      this.mouseMove = function (pos) {
          if (this.isEditable &&
                  this.currentlySelecting &&
                  (!this.isDraggable)) {
              var newMark = this.slotAt(pos);
              if (newMark !== this.endMark) {
                  this.endMark = newMark;
                  this.drawNew();
                  this.changed();
              }
          }
      };
  };
  
  StringMorph.prototype.disableSelecting = function () {
      this.mouseDownLeft = StringMorph.prototype.mouseDownLeft;
      delete this.mouseMove;
  };
  
  // TextMorph ////////////////////////////////////////////////////////////////
  
  // I am a multi-line, word-wrapping String, quasi-inheriting from StringMorph
  
  // TextMorph inherits from Morph:
  
  TextMorph.prototype = new Morph();
  TextMorph.prototype.constructor = TextMorph;
  TextMorph.uber = Morph.prototype;
  
  // TextMorph instance creation:
  
  function TextMorph(
      text,
      fontSize,
      fontStyle,
      bold,
      italic,
      alignment,
      width,
      fontName,
      shadowOffset,
      shadowColor
  ) {
      this.init(text,
          fontSize,
          fontStyle,
          bold,
          italic,
          alignment,
          width,
          fontName,
          shadowOffset,
          shadowColor);
  }
  
  TextMorph.prototype.init = function (
      text,
      fontSize,
      fontStyle,
      bold,
      italic,
      alignment,
      width,
      fontName,
      shadowOffset,
      shadowColor
  ) {
      // additional properties:
      this.text = text || (text === '' ? text : 'TextMorph');
      this.words = [];
      this.lines = [];
      this.lineSlots = [];
      this.fontSize = fontSize || 12;
      this.fontName = fontName || MorphicPreferences.globalFontFamily;
      this.fontStyle = fontStyle || 'sans-serif';
      this.isBold = bold || false;
      this.isItalic = italic || false;
      this.alignment = alignment || 'left';
      this.shadowOffset = shadowOffset || new Point(0, 0);
      this.shadowColor = shadowColor || null;
      this.maxWidth = width || 0;
      this.maxLineWidth = 0;
      this.backgroundColor = null;
      this.isEditable = false;
  
      //additional properties for ad-hoc evaluation:
      this.receiver = null;
  
      // additional properties for text-editing:
      this.isScrollable = true; // scrolls into view when edited
      this.currentlySelecting = false;
      this.startMark = 0;
      this.endMark = 0;
      this.markedTextColor = new Color(255, 255, 255);
      this.markedBackgoundColor = new Color(60, 60, 120);
  
      // initialize inherited properties:
      TextMorph.uber.init.call(this);
  
      // override inherited properites:
      this.color = new Color(0, 0, 0);
      this.noticesTransparentClick = true;
      this.drawNew();
  };
  
  TextMorph.prototype.toString = function () {
      // e.g. 'a TextMorph("Hello World")'
      return 'a TextMorph' + '("' + this.text.slice(0, 30) + '...")';
  };
  
  TextMorph.prototype.font = StringMorph.prototype.font;
  
  TextMorph.prototype.parse = function () {
      var myself = this,
          paragraphs = this.text.split('\n'),
          canvas = newCanvas(),
          context = canvas.getContext('2d'),
          oldline = '',
          newline,
          w,
          slot = 0;
  
      context.font = this.font();
      this.maxLineWidth = 0;
      this.lines = [];
      this.lineSlots = [0];
      this.words = [];
  
      paragraphs.forEach(function (p) {
          myself.words = myself.words.concat(p.split(' '));
          myself.words.push('\n');
      });
  
      this.words.forEach(function (word) {
          if (word === '\n') {
              myself.lines.push(oldline);
              myself.lineSlots.push(slot);
              myself.maxLineWidth = Math.max(
                  myself.maxLineWidth,
                  context.measureText(oldline).width
              );
              oldline = '';
          } else {
              if (myself.maxWidth > 0) {
                  newline = oldline + word + ' ';
                  w = context.measureText(newline).width;
                  if (w > myself.maxWidth) {
                      myself.lines.push(oldline);
                      myself.lineSlots.push(slot);
                      myself.maxLineWidth = Math.max(
                          myself.maxLineWidth,
                          context.measureText(oldline).width
                      );
                      oldline = word + ' ';
                  } else {
                      oldline = newline;
                  }
              } else {
                  oldline = oldline + word + ' ';
              }
              slot += word.length + 1;
          }
      });
  };
  
  TextMorph.prototype.drawNew = function () {
      var context, height, i, line, width, shadowHeight, shadowWidth,
          offx, offy, x, y, start, stop, p, c;
  
      this.image = newCanvas();
      context = this.image.getContext('2d');
      context.font = this.font();
      this.parse();
  
      // set my extent
      shadowWidth = Math.abs(this.shadowOffset.x);
      shadowHeight = Math.abs(this.shadowOffset.y);
      height = this.lines.length * (fontHeight(this.fontSize) + shadowHeight);
      if (this.maxWidth === 0) {
          this.bounds = this.bounds.origin.extent(
              new Point(this.maxLineWidth + shadowWidth, height)
          );
      } else {
          this.bounds = this.bounds.origin.extent(
              new Point(this.maxWidth + shadowWidth, height)
          );
      }
      this.image.width = this.width();
      this.image.height = this.height();
  
      // prepare context for drawing text
      context = this.image.getContext('2d');
      context.font = this.font();
      context.textAlign = 'left';
      context.textBaseline = 'bottom';
  
      // fill the background, if desired
      if (this.backgroundColor) {
          context.fillStyle = this.backgroundColor.toString();
          context.fillRect(0, 0, this.width(), this.height());
      }
  
      // draw the shadow, if any
      if (this.shadowColor) {
          offx = Math.max(this.shadowOffset.x, 0);
          offy = Math.max(this.shadowOffset.y, 0);
          context.fillStyle = this.shadowColor.toString();
  
          for (i = 0; i < this.lines.length; i = i + 1) {
              line = this.lines[i];
              width = context.measureText(line).width + shadowWidth;
              if (this.alignment === 'right') {
                  x = this.width() - width;
              } else if (this.alignment === 'center') {
                  x = (this.width() - width) / 2;
              } else { // 'left'
                  x = 0;
              }
              y = (i + 1) * (fontHeight(this.fontSize) + shadowHeight)
                  - shadowHeight;
              context.fillText(line, x + offx, y + offy);
          }
      }
  
      // now draw the actual text
      offx = Math.abs(Math.min(this.shadowOffset.x, 0));
      offy = Math.abs(Math.min(this.shadowOffset.y, 0));
      context.fillStyle = this.color.toString();
  
      for (i = 0; i < this.lines.length; i = i + 1) {
          line = this.lines[i];
          width = context.measureText(line).width + shadowWidth;
          if (this.alignment === 'right') {
              x = this.width() - width;
          } else if (this.alignment === 'center') {
              x = (this.width() - width) / 2;
          } else { // 'left'
              x = 0;
          }
          y = (i + 1) * (fontHeight(this.fontSize) + shadowHeight)
              - shadowHeight;
          context.fillText(line, x + offx, y + offy);
      }
  
      // draw the selection
      start = Math.min(this.startMark, this.endMark);
      stop = Math.max(this.startMark, this.endMark);
      for (i = start; i < stop; i += 1) {
          p = this.slotPosition(i).subtract(this.position());
          c = this.text.charAt(i);
          context.fillStyle = this.markedBackgoundColor.toString();
          context.fillRect(p.x, p.y, context.measureText(c).width + 1,
              fontHeight(this.fontSize));
          context.fillStyle = this.markedTextColor.toString();
          context.fillText(c, p.x, p.y + fontHeight(this.fontSize));
      }
  
      // notify my parent of layout change
      if (this.parent) {
          if (this.parent.layoutChanged) {
              this.parent.layoutChanged();
          }
      }
  };
  
  TextMorph.prototype.setExtent = function (aPoint) {
      this.maxWidth = Math.max(aPoint.x, 0);
      this.changed();
      this.drawNew();
  };
  
  // TextMorph mesuring:
  
  TextMorph.prototype.columnRow = function (slot) {
      // answer the logical position point of the given index ("slot")
      var row,
          col,
          idx = 0;
  
      for (row = 0; row < this.lines.length; row += 1) {
          idx = this.lineSlots[row];
          for (col = 0; col < this.lines[row].length; col += 1) {
              if (idx === slot) {
                  return new Point(col, row);
              }
              idx += 1;
          }
      }
      // return new Point(0, 0);
      return new Point(
          this.lines[this.lines.length - 1].length - 1,
          this.lines.length - 1
      );
  };
  
  TextMorph.prototype.slotPosition = function (slot) {
      // answer the physical position point of the given index ("slot")
      // where the cursor should be placed
      var colRow = this.columnRow(slot),
          context = this.image.getContext('2d'),
          shadowHeight = Math.abs(this.shadowOffset.y),
          xOffset = 0,
          yOffset,
          x,
          y,
          idx;
  
      yOffset = colRow.y * (fontHeight(this.fontSize) + shadowHeight);
      for (idx = 0; idx < colRow.x; idx += 1) {
          xOffset += context.measureText(this.lines[colRow.y][idx]).width;
      }
      x = this.left() + xOffset;
      y = this.top() + yOffset;
      return new Point(x, y);
  };
  
  TextMorph.prototype.slotAt = function (aPoint) {
      // answer the slot (index) closest to the given point taking
      // in account how far from the middle of the character it is,
      // so the cursor can be moved accordingly
  
      var charX = 0,
          row = 0,
          col = 0,
          shadowHeight = Math.abs(this.shadowOffset.y),
          context = this.image.getContext('2d');
  
      while (aPoint.y - this.top() >
              ((fontHeight(this.fontSize) + shadowHeight) * row)) {
          row += 1;
      }
      row = Math.max(row, 1);
  
      while (aPoint.x - this.left() > charX) {
          charX += context.measureText(this.lines[row - 1][col]).width;
          col += 1;
      }
  
      // see where our click fell with respect to the middle of the char
      if (aPoint.x - this.left() >
              charX - context.measureText(this.lines[row - 1][col]).width / 2) {
          return this.lineSlots[Math.max(row - 1, 0)] + col;
      } else {
          return this.lineSlots[Math.max(row - 1, 0)] + col - 1;
      }
  };
  
  TextMorph.prototype.upFrom = function (slot) {
      // answer the slot above the given one
      var above,
          colRow = this.columnRow(slot);
      if (colRow.y < 1) {
          return slot;
      }
      above = this.lines[colRow.y - 1];
      if (above.length < colRow.x - 1) {
          return this.lineSlots[colRow.y - 1] + above.length;
      }
      return this.lineSlots[colRow.y - 1] + colRow.x;
  };
  
  TextMorph.prototype.downFrom = function (slot) {
      // answer the slot below the given one
      var below,
          colRow = this.columnRow(slot);
      if (colRow.y > this.lines.length - 2) {
          return slot;
      }
      below = this.lines[colRow.y + 1];
      if (below.length < colRow.x - 1) {
          return this.lineSlots[colRow.y + 1] + below.length;
      }
      return this.lineSlots[colRow.y + 1] + colRow.x;
  };
  
  TextMorph.prototype.startOfLine = function (slot) {
      // answer the first slot (index) of the line for the given slot
      return this.lineSlots[this.columnRow(slot).y];
  };
  
  TextMorph.prototype.endOfLine = function (slot) {
      // answer the slot (index) indicating the EOL for the given slot
      return this.startOfLine(slot) +
          this.lines[this.columnRow(slot).y].length - 1;
  };
  
  TextMorph.prototype.previousWordFrom = StringMorph.prototype.previousWordFrom;
  
  TextMorph.prototype.nextWordFrom = StringMorph.prototype.nextWordFrom;
  
  // TextMorph editing:
  
  TextMorph.prototype.edit = StringMorph.prototype.edit;
  
  TextMorph.prototype.selection = StringMorph.prototype.selection;
  
  TextMorph.prototype.selectionStartSlot
      = StringMorph.prototype.selectionStartSlot;
  
  TextMorph.prototype.clearSelection = StringMorph.prototype.clearSelection;
  
  TextMorph.prototype.deleteSelection = StringMorph.prototype.deleteSelection;
  
  TextMorph.prototype.selectAll = StringMorph.prototype.selectAll;
  
  TextMorph.prototype.mouseDownLeft = StringMorph.prototype.mouseDownLeft;
  
  TextMorph.prototype.shiftClick = StringMorph.prototype.shiftClick;
  
  TextMorph.prototype.mouseClickLeft = StringMorph.prototype.mouseClickLeft;
  
  TextMorph.prototype.mouseDoubleClick = StringMorph.prototype.mouseDoubleClick;
  
  TextMorph.prototype.selectWordAt = StringMorph.prototype.selectWordAt;
  
  TextMorph.prototype.selectBetweenWordsAt
      = StringMorph.prototype.selectBetweenWordsAt;
  
  TextMorph.prototype.enableSelecting = StringMorph.prototype.enableSelecting;
  
  TextMorph.prototype.disableSelecting = StringMorph.prototype.disableSelecting;
  
  TextMorph.prototype.selectAllAndEdit = function () {
      this.edit();
      this.selectAll();
  };
  
  // TextMorph menus:
  
  TextMorph.prototype.developersMenu = function () {
      var menu = TextMorph.uber.developersMenu.call(this);
      menu.addLine();
      menu.addItem("edit", 'edit');
      menu.addItem(
          "font size...",
          function () {
              this.prompt(
                  menu.title + '\nfont\nsize:',
                  this.setFontSize,
                  this,
                  this.fontSize.toString(),
                  null,
                  6,
                  100,
                  true
              );
          },
          'set this Text\'s\nfont point size'
      );
      if (this.alignment !== 'left') {
          menu.addItem("align left", 'setAlignmentToLeft');
      }
      if (this.alignment !== 'right') {
          menu.addItem("align right", 'setAlignmentToRight');
      }
      if (this.alignment !== 'center') {
          menu.addItem("align center", 'setAlignmentToCenter');
      }
      menu.addLine();
      if (this.fontStyle !== 'serif') {
          menu.addItem("serif", 'setSerif');
      }
      if (this.fontStyle !== 'sans-serif') {
          menu.addItem("sans-serif", 'setSansSerif');
      }
      if (this.isBold) {
          menu.addItem("normal weight", 'toggleWeight');
      } else {
          menu.addItem("bold", 'toggleWeight');
      }
      if (this.isItalic) {
          menu.addItem("normal style", 'toggleItalic');
      } else {
          menu.addItem("italic", 'toggleItalic');
      }
      return menu;
  };
  
  TextMorph.prototype.setAlignmentToLeft = function () {
      this.alignment = 'left';
      this.drawNew();
      this.changed();
  };
  
  TextMorph.prototype.setAlignmentToRight = function () {
      this.alignment = 'right';
      this.drawNew();
      this.changed();
  };
  
  TextMorph.prototype.setAlignmentToCenter = function () {
      this.alignment = 'center';
      this.drawNew();
      this.changed();
  };
  
  TextMorph.prototype.toggleIsDraggable
      = StringMorph.prototype.toggleIsDraggable;
  
  TextMorph.prototype.toggleWeight = StringMorph.prototype.toggleWeight;
  
  TextMorph.prototype.toggleItalic = StringMorph.prototype.toggleItalic;
  
  TextMorph.prototype.setSerif = StringMorph.prototype.setSerif;
  
  TextMorph.prototype.setSansSerif = StringMorph.prototype.setSansSerif;
  
  TextMorph.prototype.setText = StringMorph.prototype.setText;
  
  TextMorph.prototype.setFontSize = StringMorph.prototype.setFontSize;
  
  TextMorph.prototype.numericalSetters = StringMorph.prototype.numericalSetters;
  
  // TextMorph evaluation:
  
  TextMorph.prototype.evaluationMenu = function () {
      var menu = new MenuMorph(this, null);
      menu.addItem(
          "do it",
          'doIt',
          'evaluate the\nselected expression'
      );
      menu.addItem(
          "show it",
          'showIt',
          'evaluate the\nselected expression\nand show the result'
      );
      menu.addItem(
          "inspect it",
          'inspectIt',
          'evaluate the\nselected expression\nand inspect the result'
      );
      menu.addLine();
      menu.addItem("select all", 'selectAllAndEdit');
      return menu;
  };
  
  TextMorph.prototype.setReceiver = function (obj) {
      this.receiver = obj;
      this.customContextMenu = this.evaluationMenu();
  };
  
  TextMorph.prototype.doIt = function () {
      this.receiver.evaluateString(this.selection());
      this.edit();
  };
  
  TextMorph.prototype.showIt = function () {
      var result = this.receiver.evaluateString(this.selection());
      if (result !== null) {
          this.inform(result);
      }
  };
  
  TextMorph.prototype.inspectIt = function () {
      var result = this.receiver.evaluateString(this.selection()),
          world = this.world(),
          inspector;
      if (isObject(result)) {
          inspector = new InspectorMorph(result);
          inspector.setPosition(world.hand.position());
          inspector.keepWithin(world);
          world.add(inspector);
          inspector.changed();
      }
  };
  
  // TriggerMorph ////////////////////////////////////////////////////////
  
  // I provide basic button functionality
  
  // TriggerMorph inherits from Morph:
  
  TriggerMorph.prototype = new Morph();
  TriggerMorph.prototype.constructor = TriggerMorph;
  TriggerMorph.uber = Morph.prototype;
  
  // TriggerMorph instance creation:
  
  function TriggerMorph(
      target,
      action,
      labelString,
      fontSize,
      fontStyle,
      environment,
      hint,
      labelColor,
      labelBold,
      labelItalic,
      doubleClickAction
  ) {
      this.init(
          target,
          action,
          labelString,
          fontSize,
          fontStyle,
          environment,
          hint,
          labelColor,
          labelBold,
          labelItalic,
          doubleClickAction
      );
  }
  
  TriggerMorph.prototype.init = function (
      target,
      action,
      labelString,
      fontSize,
      fontStyle,
      environment,
      hint,
      labelColor,
      labelBold,
      labelItalic,
      doubleClickAction
  ) {
      // additional properties:
      this.target = target || null;
      this.action = action || null;
      this.doubleClickAction = doubleClickAction || null;
      this.environment = environment || null;
      this.labelString = labelString || null;
      this.label = null;
      this.hint = hint || null; // null, String, or Function
      this.schedule = null; // animation slot for displaying hints
      this.fontSize = fontSize || MorphicPreferences.menuFontSize;
      this.fontStyle = fontStyle || 'sans-serif';
      this.highlightColor = new Color(192, 192, 192);
      this.pressColor = new Color(128, 128, 128);
      this.labelColor = labelColor || new Color(0, 0, 0);
      this.labelBold = labelBold || false;
      this.labelItalic = labelItalic || false;
  
      // initialize inherited properties:
      TriggerMorph.uber.init.call(this);
  
      // override inherited properites:
      this.color = new Color(255, 255, 255);
      this.drawNew();
  };
  
  // TriggerMorph drawing:
  
  TriggerMorph.prototype.drawNew = function () {
      this.createBackgrounds();
      if (this.labelString !== null) {
          this.createLabel();
      }
  };
  
  TriggerMorph.prototype.createBackgrounds = function () {
      var context,
          ext = this.extent();
  
      this.normalImage = newCanvas(ext);
      context = this.normalImage.getContext('2d');
      context.fillStyle = this.color.toString();
      context.fillRect(0, 0, ext.x, ext.y);
  
      this.highlightImage = newCanvas(ext);
      context = this.highlightImage.getContext('2d');
      context.fillStyle = this.highlightColor.toString();
      context.fillRect(0, 0, ext.x, ext.y);
  
      this.pressImage = newCanvas(ext);
      context = this.pressImage.getContext('2d');
      context.fillStyle = this.pressColor.toString();
      context.fillRect(0, 0, ext.x, ext.y);
  
      this.image = this.normalImage;
  };
  
  TriggerMorph.prototype.createLabel = function () {
      if (this.label !== null) {
          this.label.destroy();
      }
      this.label = new StringMorph(
          this.labelString,
          this.fontSize,
          this.fontStyle,
          this.labelBold,
          this.labelItalic,
          false, // numeric
          null, // shadow offset
          null, // shadow color
          this.labelColor
      );
      this.label.setPosition(
          this.center().subtract(
              this.label.extent().floorDivideBy(2)
          )
      );
      this.add(this.label);
  };
  
  // TriggerMorph action:
  
  TriggerMorph.prototype.trigger = function () {
      /*
      if target is a function, use it as callback:
      execute target as callback function with action as argument
      in the environment as optionally specified.
      Note: if action is also a function, instead of becoming
      the argument itself it will be called to answer the argument.
      for selections, Yes/No Choices etc. As second argument pass
      myself, so I can be modified to reflect status changes, e.g.
      inside a list box:
  
      else (if target is not a function):
  
          if action is a function:
          execute the action with target as environment (can be null)
          for lambdafied (inline) actions
  
          else if action is a String:
          treat it as function property of target and execute it
          for selector-like actions
      */
      if (this.schedule) {
          this.schedule.isActive = false;
      }
      if (typeof this.target === 'function') {
          if (typeof this.action === 'function') {
              this.target.call(this.environment, this.action.call(), this);
          } else {
              this.target.call(this.environment, this.action, this);
          }
      } else {
          if (typeof this.action === 'function') {
              this.action.call(this.target);
          } else { // assume it's a String
              this.target[this.action]();
          }
      }
  };
  
  TriggerMorph.prototype.triggerDoubleClick = function () {
      // same as trigger() but use doubleClickAction instead of action property
      // note that specifying a doubleClickAction is optional
      if (!this.doubleClickAction) {return; }
      if (this.schedule) {
          this.schedule.isActive = false;
      }
      if (typeof this.target === 'function') {
          if (typeof this.doubleClickAction === 'function') {
              this.target.call(
                  this.environment,
                  this.doubleClickAction.call(),
                  this
              );
          } else {
              this.target.call(this.environment, this.doubleClickAction, this);
          }
      } else {
          if (typeof this.doubleClickAction === 'function') {
              this.doubleClickAction.call(this.target);
          } else { // assume it's a String
              this.target[this.doubleClickAction]();
          }
      }
  };
  
  // TriggerMorph events:
  
  TriggerMorph.prototype.mouseEnter = function () {
      var contents = this.hint instanceof Function ? this.hint() : this.hint;
      this.image = this.highlightImage;
      this.changed();
      if (contents) {
          this.bubbleHelp(contents);
      }
  };
  
  TriggerMorph.prototype.mouseLeave = function () {
      this.image = this.normalImage;
      this.changed();
      if (this.schedule) {
          this.schedule.isActive = false;
      }
      if (this.hint) {
          this.world().hand.destroyTemporaries();
      }
  };
  
  TriggerMorph.prototype.mouseDownLeft = function () {
      this.image = this.pressImage;
      this.changed();
  };
  
  TriggerMorph.prototype.mouseClickLeft = function () {
      this.image = this.highlightImage;
      this.changed();
      this.trigger();
  };
  
  TriggerMorph.prototype.mouseDoubleClick = function () {
      this.triggerDoubleClick();
  };
  
  TriggerMorph.prototype.rootForGrab = function () {
      return this.isDraggable ? TriggerMorph.uber.rootForGrab.call(this) : null;
  };
  
  // TriggerMorph bubble help:
  
  TriggerMorph.prototype.bubbleHelp = function (contents) {
      var world = this.world(),
          myself = this;
      this.schedule = new Animation(
          nop,
          nop,
          0,
          500,
          nop,
          function () {myself.popUpbubbleHelp(contents); }
      );
      world.animations.push(this.schedule);
  };
  
  TriggerMorph.prototype.popUpbubbleHelp = function (contents) {
      new SpeechBubbleMorph(
          localize(contents),
          null,
          null,
          1
      ).popUp(this.world(), this.rightCenter().add(new Point(-8, 0)));
  };
  
  // MenuItemMorph ///////////////////////////////////////////////////////
  
  // I automatically determine my bounds
  
  var MenuItemMorph;
  
  // MenuItemMorph inherits from TriggerMorph:
  
  MenuItemMorph.prototype = new TriggerMorph();
  MenuItemMorph.prototype.constructor = MenuItemMorph;
  MenuItemMorph.uber = TriggerMorph.prototype;
  
  // MenuItemMorph instance creation:
  
  function MenuItemMorph(
      target,
      action,
      labelString, // can also be a Morph or a Canvas or a tuple: [icon, string]
      fontSize,
      fontStyle,
      environment,
      hint,
      color,
      bold,
      italic,
      doubleClickAction, // optional when used as list morph item
      shortcut // optional string, Morph, Canvas or tuple: [icon, string]
  ) {
      // additional properties:
      this.shortcutString = shortcut || null;
      this.shortcut = null;
  
      // initialize inherited properties:
      this.init(
          target,
          action,
          labelString,
          fontSize,
          fontStyle,
          environment,
          hint,
          color,
          bold,
          italic,
          doubleClickAction
      );
  }
  
  MenuItemMorph.prototype.createLabel = function () {
      var w, h;
      if (this.label) {
          this.label.destroy();
      }
      this.label = this.createLabelPart(this.labelString);
      this.add(this.label);
      w = this.label.width();
      h = this.label.height();
      if (this.shortcut) {
          this.shortcut.destroy();
      }
      if (this.shortcutString) {
          this.shortcut = this.createLabelPart(this.shortcutString);
          w += this.shortcut.width() + 4;
          h = Math.max(h, this.shortcut.height());
          this.add(this.shortcut);
      }
      this.silentSetExtent(new Point(w + 8, h));
      this.fixLayout();
  };
  
  MenuItemMorph.prototype.fixLayout = function () {
      var cntr = this.center();
      this.label.setCenter(cntr);
      this.label.setLeft(this.left() + 4);
      if (this.shortcut) {
          this.shortcut.setCenter(cntr);
          this.shortcut.setRight(this.right() - 4);
      }
  };
  
  MenuItemMorph.prototype.createLabelPart = function (source) {
      var part, icon, lbl;
      if (isString(source)) {
          return this.createLabelString(source);
      }
      if (source instanceof Array) {
          // assume its pattern is: [icon, string]
          part = new Morph();
          part.alpha = 0; // transparent
          icon = this.createIcon(source[0]);
          part.add(icon);
          lbl = this.createLabelString(source[1]);
          part.add(lbl);
          lbl.setCenter(icon.center());
          lbl.setLeft(icon.right() + 4);
          part.bounds = (icon.bounds.merge(lbl.bounds));
          part.drawNew();
          return part;
      }
      // assume it's either a Morph or a Canvas
      return this.createIcon(source);
  };
  
  MenuItemMorph.prototype.createIcon = function (source) {
      // source can be either a Morph or an HTMLCanvasElement
      var icon = new Morph(),
          src;
      icon.image = source instanceof Morph ? source.fullImage() : source;
      // adjust shadow dimensions
      if (source instanceof Morph && source.getShadow()) {
          src = icon.image;
          icon.image = newCanvas(
              source.fullBounds().extent().subtract(
                  this.shadowBlur * (useBlurredShadows ? 1 : 2)
              )
          );
          icon.image.getContext('2d').drawImage(src, 0, 0);
      }
      icon.silentSetWidth(icon.image.width);
      icon.silentSetHeight(icon.image.height);
      return icon;
  };
  
  MenuItemMorph.prototype.createLabelString = function (string) {
      var lbl = new TextMorph(
          string,
          this.fontSize,
          this.fontStyle,
          this.labelBold,
          this.labelItalic
      );
      lbl.setColor(this.labelColor);
      return lbl;
  };
  
  // MenuItemMorph events:
  
  MenuItemMorph.prototype.mouseEnter = function () {
      var menu = this.parentThatIsA(MenuMorph);
      if (this.isShowingSubmenu()) {
          return;
      }
      if (menu) {
          menu.closeSubmenu();
      }
      if (!this.isListItem()) {
          this.image = this.highlightImage;
          this.changed();
      }
      if (this.action instanceof MenuMorph) {
          this.delaySubmenu();
      } else if (this.hint) {
          this.bubbleHelp(this.hint);
      }
  };
  
  MenuItemMorph.prototype.mouseLeave = function () {
      if (!this.isListItem()) {
          if (this.isShowingSubmenu()) {
              this.image = this.highlightImage;
          } else {
              this.image = this.normalImage;
          }
          this.changed();
      }
      if (this.schedule) {
          this.schedule.isActive = false;
      }
      if (this.hint) {
          this.world().hand.destroyTemporaries();
      }
  };
  
  MenuItemMorph.prototype.mouseDownLeft = function (pos) {
      if (this.isListItem()) {
          this.parentThatIsA(MenuMorph).unselectAllItems();
          this.escalateEvent('mouseDownLeft', pos);
      }
      this.image = this.pressImage;
      this.changed();
  };
  
  MenuItemMorph.prototype.mouseMove = function () {
      if (this.isListItem()) {
          this.escalateEvent('mouseMove');
      }
  };
  
  MenuItemMorph.prototype.mouseClickLeft = function () {
      if (this.action instanceof MenuMorph) {
          this.popUpSubmenu();
      } else {
          if (!this.isListItem()) {
              this.parentThatIsA(MenuMorph).closeRootMenu();
              this.world().activeMenu = null;
          }
          this.trigger();
      }
  };
  
  MenuItemMorph.prototype.isListItem = function () {
  	var menu = this.parentThatIsA(MenuMorph);
      if (menu) {
          return menu.isListContents;
      }
      return false;
  };
  
  MenuItemMorph.prototype.isSelectedListItem = function () {
      if (this.isListItem()) {
          return this.image === this.pressImage;
      }
      return false;
  };
  
  MenuItemMorph.prototype.isShowingSubmenu = function () {
      var menu = this.parentThatIsA(MenuMorph);
      if (menu && (this.action instanceof MenuMorph)) {
          return menu.submenu === this.action;
      }
      return false;
  };
  
  // MenuItemMorph submenus:
  
  MenuItemMorph.prototype.delaySubmenu = function () {
      var world = this.world(),
          myself = this;
      this.schedule = new Animation(
          nop,
          nop,
          0,
          500,
          nop,
          function () {myself.popUpSubmenu(); }
      );
      world.animations.push(this.schedule);
  };
  
  MenuItemMorph.prototype.popUpSubmenu = function () {
      var menu = this.parentThatIsA(MenuMorph);
      if (!(this.action instanceof MenuMorph)) {return; }
      this.action.drawNew();
      this.action.setPosition(this.topRight().subtract(new Point(0, 5)));
      this.action.addShadow(new Point(2, 2), 80);
      this.action.keepWithin(this.world());
      if (this.action.items.length < 1 && !this.action.title) {return; }
      menu.add(this.action);
      menu.submenu = this.action;
      menu.submenu.world = menu.world; // keyboard control
      this.action.fullChanged();
  };
  
  // FrameMorph //////////////////////////////////////////////////////////
  
  // I clip my submorphs at my bounds
  
  // Frames inherit from Morph:
  
  FrameMorph.prototype = new Morph();
  FrameMorph.prototype.constructor = FrameMorph;
  FrameMorph.uber = Morph.prototype;
  
  function FrameMorph(aScrollFrame) {
      this.init(aScrollFrame);
  }
  
  FrameMorph.prototype.init = function (aScrollFrame) {
      this.scrollFrame = aScrollFrame || null;
  
      FrameMorph.uber.init.call(this);
      this.color = new Color(255, 250, 245);
      this.drawNew();
      this.acceptsDrops = true;
  
      if (this.scrollFrame) {
          this.isDraggable = false;
          this.noticesTransparentClick = false;
          this.alpha = 0;
      }
  };
  
  FrameMorph.prototype.fullBounds = function () {
      var shadow = this.getShadow();
      if (shadow !== null) {
          return this.bounds.merge(shadow.bounds);
      }
      return this.bounds;
  };
  
  FrameMorph.prototype.fullImage = function () {
      // use only for shadows
      return this.image;
  };
  
  FrameMorph.prototype.fullDrawOn = function (aCanvas, aRect) {
      var rectangle, dirty;
      if (!this.isVisible) {
          return null;
      }
      rectangle = aRect || this.fullBounds();
      dirty = this.bounds.intersect(rectangle);
      if (!dirty.extent().gt(new Point(0, 0))) {
          return null;
      }
      this.drawOn(aCanvas, dirty);
      this.children.forEach(function (child) {
          if (child instanceof ShadowMorph) {
              child.fullDrawOn(aCanvas, rectangle);
          } else {
              child.fullDrawOn(aCanvas, dirty);
          }
      });
  };
  
  // FrameMorph navigation:
  
  FrameMorph.prototype.topMorphAt = function (point) {
      var i, result;
      if (!(this.isVisible && this.bounds.containsPoint(point))) {
          return null;
      }
      for (i = this.children.length - 1; i >= 0; i -= 1) {
          result = this.children[i].topMorphAt(point);
          if (result) {return result; }
      }
      return this.noticesTransparentClick ||
          !this.isTransparentAt(point) ? this : null;
  };
  
  // FrameMorph scrolling support:
  
  FrameMorph.prototype.submorphBounds = function () {
      var result = null;
  
      if (this.children.length > 0) {
          result = this.children[0].bounds;
          this.children.forEach(function (child) {
              result = result.merge(child.fullBounds());
          });
      }
      return result;
  };
  
  FrameMorph.prototype.keepInScrollFrame = function () {
      if (this.scrollFrame === null) {
          return null;
      }
      if (this.left() > this.scrollFrame.left()) {
          this.moveBy(
              new Point(this.scrollFrame.left() - this.left(), 0)
          );
      }
      if (this.right() < this.scrollFrame.right()) {
          this.moveBy(
              new Point(this.scrollFrame.right() - this.right(), 0)
          );
      }
      if (this.top() > this.scrollFrame.top()) {
          this.moveBy(
              new Point(0, this.scrollFrame.top() - this.top())
          );
      }
      if (this.bottom() < this.scrollFrame.bottom()) {
          this.moveBy(
              0,
              new Point(this.scrollFrame.bottom() - this.bottom(), 0)
          );
      }
  };
  
  FrameMorph.prototype.adjustBounds = function () {
      var subBounds,
          newBounds,
          myself = this;
  
      if (this.scrollFrame === null) {
          return null;
      }
  
      subBounds = this.submorphBounds();
      if (subBounds && (!this.scrollFrame.isTextLineWrapping)) {
          newBounds = subBounds
              .expandBy(this.scrollFrame.padding)
              .growBy(this.scrollFrame.growth)
              .merge(this.scrollFrame.bounds);
      } else {
          newBounds = this.scrollFrame.bounds.copy();
      }
      if (!this.bounds.eq(newBounds)) {
          this.bounds = newBounds;
          this.drawNew();
          this.keepInScrollFrame();
      }
  
      if (this.scrollFrame.isTextLineWrapping) {
          this.children.forEach(function (morph) {
              if (morph instanceof TextMorph) {
                  morph.setWidth(myself.width());
                  myself.setHeight(
                      Math.max(morph.height(), myself.scrollFrame.height())
                  );
              }
          });
      }
  
      this.scrollFrame.adjustScrollBars();
  };
  
  // FrameMorph dragging & dropping of contents:
  
  FrameMorph.prototype.reactToDropOf = function () {
      this.adjustBounds();
  };
  
  FrameMorph.prototype.reactToGrabOf = function () {
      this.adjustBounds();
  };
  
  // FrameMorph menus:
  
  FrameMorph.prototype.developersMenu = function () {
      var menu = FrameMorph.uber.developersMenu.call(this);
      if (this.children.length > 0) {
          menu.addLine();
          menu.addItem(
              "move all inside...",
              'keepAllSubmorphsWithin',
              'keep all submorphs\nwithin and visible'
          );
      }
      return menu;
  };
  
  FrameMorph.prototype.keepAllSubmorphsWithin = function () {
      var myself = this;
      this.children.forEach(function (m) {
          m.keepWithin(myself);
      });
  };
  
  // ScrollFrameMorph ////////////////////////////////////////////////////
  
  ScrollFrameMorph.prototype = new FrameMorph();
  ScrollFrameMorph.prototype.constructor = ScrollFrameMorph;
  ScrollFrameMorph.uber = FrameMorph.prototype;
  
  function ScrollFrameMorph(scroller, size, sliderColor) {
      this.init(scroller, size, sliderColor);
  }
  
  ScrollFrameMorph.prototype.init = function (scroller, size, sliderColor) {
      var myself = this;
  
      ScrollFrameMorph.uber.init.call(this);
      this.scrollBarSize = size || MorphicPreferences.scrollBarSize;
      this.autoScrollTrigger = null;
      this.enableAutoScrolling = true; // change to suppress
      this.isScrollingByDragging = true; // change to suppress
      this.hasVelocity = true; // dto.
      this.padding = 0; // around the scrollable area
      this.growth = 0; // pixels or Point to grow right/left when near edge
      this.isTextLineWrapping = false;
      this.contents = scroller || new FrameMorph(this);
      this.add(this.contents);
      this.hBar = new SliderMorph(
          null, // start
          null, // stop
          null, // value
          null, // size
          'horizontal',
          sliderColor
      );
      this.hBar.setHeight(this.scrollBarSize);
      this.hBar.action = function (num) {
          myself.contents.setPosition(
              new Point(
                  myself.left() - num,
                  myself.contents.position().y
              )
          );
      };
      this.hBar.isDraggable = false;
      this.add(this.hBar);
      this.vBar = new SliderMorph(
          null, // start
          null, // stop
          null, // value
          null, // size
          'vertical',
          sliderColor
      );
      this.vBar.setWidth(this.scrollBarSize);
      this.vBar.action = function (num) {
          myself.contents.setPosition(
              new Point(
                  myself.contents.position().x,
                  myself.top() - num
              )
          );
      };
      this.vBar.isDraggable = false;
      this.add(this.vBar);
      this.toolBar = null; // optional slot
  };
  
  ScrollFrameMorph.prototype.adjustScrollBars = function () {
      var hWidth = this.width() - this.scrollBarSize,
          vHeight = this.height() - this.scrollBarSize;
  
      this.changed();
      if (this.contents.width() > this.width() +
              MorphicPreferences.scrollBarSize) {
          this.hBar.show();
          if (this.hBar.width() !== hWidth) {
              this.hBar.setWidth(hWidth);
          }
  
          this.hBar.setPosition(
              new Point(
                  this.left(),
                  this.bottom() - this.hBar.height()
              )
          );
          this.hBar.start = 0;
          this.hBar.stop = this.contents.width() - this.width();
          this.hBar.size =
              this.width() / this.contents.width() * this.hBar.stop;
          this.hBar.value = this.left() - this.contents.left();
          this.hBar.drawNew();
      } else {
          this.hBar.hide();
      }
  
      if (this.contents.height() > this.height() +
              this.scrollBarSize) {
          this.vBar.show();
          if (this.vBar.height() !== vHeight) {
              this.vBar.setHeight(vHeight);
          }
  
          this.vBar.setPosition(
              new Point(
                  this.right() - this.vBar.width(),
                  this.top()
              )
          );
          this.vBar.start = 0;
          this.vBar.stop = this.contents.height() - this.height();
          this.vBar.size =
              this.height() / this.contents.height() * this.vBar.stop;
          this.vBar.value = this.top() - this.contents.top();
          this.vBar.drawNew();
      } else {
          this.vBar.hide();
      }
      this.adjustToolBar();
  };
  
  ScrollFrameMorph.prototype.adjustToolBar = function () {
      var padding = 3;
      if (this.toolBar) {
          this.toolBar.setTop(this.top() + padding);
          this.toolBar.setRight(
              (this.vBar.isVisible ? this.vBar.left() : this.right()) - padding
          );
      }
  };
  
  ScrollFrameMorph.prototype.addContents = function (aMorph) {
      this.contents.add(aMorph);
      this.contents.adjustBounds();
  };
  
  ScrollFrameMorph.prototype.setContents = function (aMorph) {
      this.contents.children.forEach(function (m) {
          m.destroy();
      });
      this.contents.children = [];
      aMorph.setPosition(this.position().add(this.padding + 2));
      this.addContents(aMorph);
  };
  
  ScrollFrameMorph.prototype.setExtent = function (aPoint) {
      if (this.isTextLineWrapping) {
          this.contents.setPosition(this.position().copy());
      }
      ScrollFrameMorph.uber.setExtent.call(this, aPoint);
      this.contents.adjustBounds();
  };
  
  // ScrollFrameMorph scrolling by dragging:
  
  ScrollFrameMorph.prototype.scrollX = function (steps) {
      var cl = this.contents.left(),
          l = this.left(),
          cw = this.contents.width(),
          r = this.right(),
          newX;
  
      newX = cl + steps;
      if (newX + cw < r) {
          newX = r - cw;
      }
      if (newX > l) {
          newX = l;
      }
      if (newX !== cl) {
          this.contents.setLeft(newX);
      }
  };
  
  ScrollFrameMorph.prototype.scrollY = function (steps) {
      var ct = this.contents.top(),
          t = this.top(),
          ch = this.contents.height(),
          b = this.bottom(),
          newY;
  
      newY = ct + steps;
      if (newY + ch < b) {
          newY = b - ch;
      }
      if (newY > t) {
          newY = t;
      }
      if (newY !== ct) {
          this.contents.setTop(newY);
      }
  };
  
  ScrollFrameMorph.prototype.step = nop;
  
  ScrollFrameMorph.prototype.mouseDownLeft = function (pos) {
      if (!this.isScrollingByDragging) {
          return null;
      }
      var world = this.root(),
          hand = world.hand,
          oldPos = pos,
          myself = this,
          deltaX = 0,
          deltaY = 0,
          friction = 0.8;
  
      this.step = function () {
          var newPos;
          if (hand.mouseButton &&
                  (hand.children.length === 0) &&
                  (myself.bounds.containsPoint(hand.bounds.origin))) {
  
              if (hand.grabPosition &&
                  (hand.grabPosition.distanceTo(hand.position()) <=
                      MorphicPreferences.grabThreshold)) {
                  // still within the grab threshold
                  return null;
              }
  
              newPos = hand.bounds.origin;
              deltaX = newPos.x - oldPos.x;
              if (deltaX !== 0) {
                  myself.scrollX(deltaX);
              }
              deltaY = newPos.y - oldPos.y;
              if (deltaY !== 0) {
                  myself.scrollY(deltaY);
              }
              oldPos = newPos;
          } else {
              if (!myself.hasVelocity) {
                  myself.step = function () {
                      nop();
                  };
              } else {
                  if ((Math.abs(deltaX) < 0.5) &&
                          (Math.abs(deltaY) < 0.5)) {
                      myself.step = function () {
                          nop();
                      };
                  } else {
                      deltaX = deltaX * friction;
                      myself.scrollX(Math.round(deltaX));
                      deltaY = deltaY * friction;
                      myself.scrollY(Math.round(deltaY));
                  }
              }
          }
          this.adjustScrollBars();
      };
  };
  
  ScrollFrameMorph.prototype.startAutoScrolling = function () {
      var myself = this,
          inset = MorphicPreferences.scrollBarSize * 3,
          world = this.world(),
          hand,
          inner,
          pos;
  
      if (!world) {
          return null;
      }
      hand = world.hand;
      if (!this.autoScrollTrigger) {
          this.autoScrollTrigger = Date.now();
      }
      this.step = function () {
          pos = hand.bounds.origin;
          inner = myself.bounds.insetBy(inset);
          if ((myself.bounds.containsPoint(pos)) &&
                  (!(inner.containsPoint(pos))) &&
                  (hand.children.length > 0)) {
              myself.autoScroll(pos);
          } else {
              myself.step = function () {
                  nop();
              };
              myself.autoScrollTrigger = null;
          }
      };
  };
  
  ScrollFrameMorph.prototype.autoScroll = function (pos) {
      var inset, area;
  
      if (Date.now() - this.autoScrollTrigger < 500) {
          return null;
      }
  
      inset = MorphicPreferences.scrollBarSize * 3;
      area = this.topLeft().extent(new Point(this.width(), inset));
      if (area.containsPoint(pos)) {
          this.scrollY(inset - (pos.y - this.top()));
      }
      area = this.topLeft().extent(new Point(inset, this.height()));
      if (area.containsPoint(pos)) {
          this.scrollX(inset - (pos.x - this.left()));
      }
      area = (new Point(this.right() - inset, this.top()))
          .extent(new Point(inset, this.height()));
      if (area.containsPoint(pos)) {
          this.scrollX(-(inset - (this.right() - pos.x)));
      }
      area = (new Point(this.left(), this.bottom() - inset))
          .extent(new Point(this.width(), inset));
      if (area.containsPoint(pos)) {
          this.scrollY(-(inset - (this.bottom() - pos.y)));
      }
      this.adjustScrollBars();
  };
  
  // ScrollFrameMorph scrolling by editing text:
  
  ScrollFrameMorph.prototype.scrollCursorIntoView = function (morph) {
      var txt = morph.target,
          offset = txt.position().subtract(this.contents.position()),
          ft = this.top() + this.padding,
          fb = this.bottom() - this.padding;
      this.contents.setExtent(txt.extent().add(offset).add(this.padding));
      if (morph.top() < ft) {
          this.contents.setTop(this.contents.top() + ft - morph.top());
          morph.setTop(ft);
      } else if (morph.bottom() > fb) {
          this.contents.setBottom(this.contents.bottom() + fb - morph.bottom());
          morph.setBottom(fb);
      }
      this.adjustScrollBars();
  };
  
  // ScrollFrameMorph events:
  
  ScrollFrameMorph.prototype.mouseScroll = function (y, x) {
      if (y) {
          this.scrollY(y * MorphicPreferences.mouseScrollAmount);
      }
      if (x) {
          this.scrollX(x * MorphicPreferences.mouseScrollAmount);
      }
      this.adjustScrollBars();
  };
  
  // ScrollFrameMorph duplicating:
  
  ScrollFrameMorph.prototype.updateReferences = function (map) {
      var myself = this;
      ScrollFrameMorph.uber.updateReferences.call(this, map);
      if (this.hBar) {
          this.hBar.action = function (num) {
              myself.contents.setPosition(
                  new Point(myself.left() - num, myself.contents.position().y)
              );
          };
      }
      if (this.vBar) {
          this.vBar.action = function (num) {
              myself.contents.setPosition(
                  new Point(myself.contents.position().x, myself.top() - num)
              );
          };
      }
  };
  
  // ScrollFrameMorph menu:
  
  ScrollFrameMorph.prototype.developersMenu = function () {
      var menu = ScrollFrameMorph.uber.developersMenu.call(this);
      if (this.isTextLineWrapping) {
          menu.addItem(
              "auto line wrap off...",
              'toggleTextLineWrapping',
              'turn automatic\nline wrapping\noff'
          );
      } else {
          menu.addItem(
              "auto line wrap on...",
              'toggleTextLineWrapping',
              'enable automatic\nline wrapping'
          );
      }
      return menu;
  };
  
  ScrollFrameMorph.prototype.toggleTextLineWrapping = function () {
      this.isTextLineWrapping = !this.isTextLineWrapping;
  };
  
  // ListMorph ///////////////////////////////////////////////////////////
  
  ListMorph.prototype = new ScrollFrameMorph();
  ListMorph.prototype.constructor = ListMorph;
  ListMorph.uber = ScrollFrameMorph.prototype;
  
  function ListMorph(elements, labelGetter, format, doubleClickAction) {
  /*
      passing a format is optional. If the format parameter is specified
      it has to be of the following pattern:
  
          [
              [<color>, <single-argument predicate>],
              ['bold', <single-argument predicate>],
              ['italic', <single-argument predicate>],
              ...
          ]
  
      multiple conditions can be passed in such a format list, the
      last predicate to evaluate true when given the list element sets
      the given format category (color, bold, italic).
      If no condition is met, the default format (color black, non-bold,
      non-italic) will be assigned.
  
      An example of how to use fomats can be found in the InspectorMorph's
      "markOwnProperties" mechanism.
  */
      this.init(
          elements || [],
          labelGetter || function (element) {
              if (isString(element)) {
                  return element;
              }
              if (element.toSource) {
                  return element.toSource();
              }
              return element.toString();
          },
          format || [],
          doubleClickAction // optional callback
      );
  }
  
  ListMorph.prototype.init = function (
      elements,
      labelGetter,
      format,
      doubleClickAction
  ) {
      ListMorph.uber.init.call(this);
  
      this.contents.acceptsDrops = false;
      this.color = new Color(255, 255, 255);
      this.hBar.alpha = 0.6;
      this.vBar.alpha = 0.6;
      this.elements = elements || [];
      this.labelGetter = labelGetter;
      this.format = format;
      this.listContents = null;
      this.selected = null; // actual element currently selected
      this.active = null; // menu item representing the selected element
      this.action = null;
      this.doubleClickAction = doubleClickAction || null;
      this.acceptsDrops = false;
      this.buildListContents();
  };
  
  ListMorph.prototype.buildListContents = function () {
      var myself = this;
      if (this.listContents) {
          this.listContents.destroy();
      }
      this.listContents = new MenuMorph(
          this.select,
          null,
          this
      );
      if (this.elements.length === 0) {
          this.elements = ['(empty)'];
      }
      this.elements.forEach(function (element) {
          var color = null,
              bold = false,
              italic = false;
  
          myself.format.forEach(function (pair) {
              if (pair[1].call(null, element)) {
                  if (pair[0] === 'bold') {
                      bold = true;
                  } else if (pair[0] === 'italic') {
                      italic = true;
                  } else { // assume it's a color
                      color = pair[0];
                  }
              }
          });
          myself.listContents.addItem(
              myself.labelGetter(element), // label string
              element, // action
              null, // hint
              color,
              bold,
              italic,
              myself.doubleClickAction
          );
      });
      this.listContents.isListContents = true;
      this.listContents.drawNew();
      this.listContents.setPosition(this.contents.position());
      this.addContents(this.listContents);
  };
  
  ListMorph.prototype.select = function (item, trigger) {
      if (isNil(item)) {return; }
      this.selected = item;
      this.active = trigger;
      if (this.action) {
          this.action.call(null, item);
      }
  };
  
  ListMorph.prototype.setExtent = function (aPoint) {
      var lb = this.listContents.bounds,
          nb = this.bounds.origin.copy().corner(
              this.bounds.origin.add(aPoint)
          );
  
      if (nb.right() > lb.right() && nb.width() <= lb.width()) {
          this.listContents.setRight(nb.right());
      }
      if (nb.bottom() > lb.bottom() && nb.height() <= lb.height()) {
          this.listContents.setBottom(nb.bottom());
      }
      ListMorph.uber.setExtent.call(this, aPoint);
  };
  
  ListMorph.prototype.activeIndex = function () {
      return this.listContents.children.indexOf(this.active);
  };
  
  ListMorph.prototype.activateIndex = function (idx) {
      var item = this.listContents.children[idx];
      if (!item) {return; }
      item.image = item.pressImage;
      item.changed();
      item.trigger();
  };
  
  // StringFieldMorph ////////////////////////////////////////////////////
  
  // StringFieldMorph inherit from FrameMorph:
  
  StringFieldMorph.prototype = new FrameMorph();
  StringFieldMorph.prototype.constructor = StringFieldMorph;
  StringFieldMorph.uber = FrameMorph.prototype;
  
  function StringFieldMorph(
      defaultContents,
      minWidth,
      fontSize,
      fontStyle,
      bold,
      italic,
      isNumeric
  ) {
      this.init(
          defaultContents || '',
          minWidth || 100,
          fontSize || 12,
          fontStyle || 'sans-serif',
          bold || false,
          italic || false,
          isNumeric
      );
  }
  
  StringFieldMorph.prototype.init = function (
      defaultContents,
      minWidth,
      fontSize,
      fontStyle,
      bold,
      italic,
      isNumeric
  ) {
      this.defaultContents = defaultContents;
      this.minWidth = minWidth;
      this.fontSize = fontSize;
      this.fontStyle = fontStyle;
      this.isBold = bold;
      this.isItalic = italic;
      this.isNumeric = isNumeric || false;
      this.text = null;
      StringFieldMorph.uber.init.call(this);
      this.color = new Color(255, 255, 255);
      this.isEditable = true;
      this.acceptsDrops = false;
      this.drawNew();
  };
  
  StringFieldMorph.prototype.drawNew = function () {
      var txt;
      txt = this.text ? this.string() : this.defaultContents;
      this.text = null;
      this.children.forEach(function (child) {
          child.destroy();
      });
      this.children = [];
      this.text = new StringMorph(
          txt,
          this.fontSize,
          this.fontStyle,
          this.isBold,
          this.isItalic,
          this.isNumeric
      );
  
      this.text.isNumeric = this.isNumeric; // for whichever reason...
      this.text.setPosition(this.bounds.origin.copy());
      this.text.isEditable = this.isEditable;
      this.text.isDraggable = false;
      this.text.enableSelecting();
      this.silentSetExtent(
          new Point(
              Math.max(this.width(), this.minWidth),
              this.text.height()
          )
      );
      StringFieldMorph.uber.drawNew.call(this);
      this.add(this.text);
  };
  
  StringFieldMorph.prototype.string = function () {
      return this.text.text;
  };
  
  StringFieldMorph.prototype.mouseClickLeft = function (pos) {
      if (this.isEditable) {
          this.text.edit();
      } else {
          this.escalateEvent('mouseClickLeft', pos);
      }
  };
  
  // BouncerMorph ////////////////////////////////////////////////////////
  
  // I am a Demo of a stepping custom Morph
  
  var BouncerMorph;
  
  // Bouncers inherit from Morph:
  
  BouncerMorph.prototype = new Morph();
  BouncerMorph.prototype.constructor = BouncerMorph;
  BouncerMorph.uber = Morph.prototype;
  
  // BouncerMorph instance creation:
  
  function BouncerMorph() {
      this.init();
  }
  
  // BouncerMorph initialization:
  
  BouncerMorph.prototype.init = function (type, speed) {
      BouncerMorph.uber.init.call(this);
      this.fps = 50;
  
      // additional properties:
      this.isStopped = false;
      this.type = type || 'vertical';
      if (this.type === 'vertical') {
          this.direction = 'down';
      } else {
          this.direction = 'right';
      }
      this.speed = speed || 1;
  };
  
  // BouncerMorph moving:
  
  BouncerMorph.prototype.moveUp = function () {
      this.moveBy(new Point(0, -this.speed));
  };
  
  BouncerMorph.prototype.moveDown = function () {
      this.moveBy(new Point(0, this.speed));
  };
  
  BouncerMorph.prototype.moveRight = function () {
      this.moveBy(new Point(this.speed, 0));
  };
  
  BouncerMorph.prototype.moveLeft = function () {
      this.moveBy(new Point(-this.speed, 0));
  };
  
  // BouncerMorph stepping:
  
  BouncerMorph.prototype.step = function () {
      if (!this.isStopped) {
          if (this.type === 'vertical') {
              if (this.direction === 'down') {
                  this.moveDown();
              } else {
                  this.moveUp();
              }
              if (this.fullBounds().top() < this.parent.top() &&
                      this.direction === 'up') {
                  this.direction = 'down';
              }
              if (this.fullBounds().bottom() > this.parent.bottom() &&
                      this.direction === 'down') {
                  this.direction = 'up';
              }
          } else if (this.type === 'horizontal') {
              if (this.direction === 'right') {
                  this.moveRight();
              } else {
                  this.moveLeft();
              }
              if (this.fullBounds().left() < this.parent.left() &&
                      this.direction === 'left') {
                  this.direction = 'right';
              }
              if (this.fullBounds().right() > this.parent.right() &&
                      this.direction === 'right') {
                  this.direction = 'left';
              }
          }
      }
  };
  
  // HandMorph ///////////////////////////////////////////////////////////
  
  // I represent the Mouse cursor
  
  // HandMorph inherits from Morph:
  
  HandMorph.prototype = new Morph();
  HandMorph.prototype.constructor = HandMorph;
  HandMorph.uber = Morph.prototype;
  
  // HandMorph instance creation:
  
  function HandMorph(aWorld) {
      this.init(aWorld);
  }
  
  // HandMorph initialization:
  
  HandMorph.prototype.init = function (aWorld) {
      HandMorph.uber.init.call(this, true);
      this.bounds = new Rectangle();
  
      // additional properties:
      this.world = aWorld;
      this.mouseButton = null;
      this.mouseOverList = [];
      this.morphToGrab = null;
      this.grabPosition = null;
      this.grabOrigin = null;
      this.temporaries = [];
      this.touchHoldTimeout = null;
      this.contextMenuEnabled = false;
  };
  
  HandMorph.prototype.changed = function () {
      var b;
      if (this.world !== null) {
          b = this.fullBounds();
          if (!b.extent().eq(new Point())) {
              this.world.broken.push(b.spread());
          }
      }
  };
  
  HandMorph.prototype.fullChanged = HandMorph.prototype.changed;
  
  // HandMorph navigation:
  
  HandMorph.prototype.morphAtPointer = function () {
      return this.world.topMorphAt(this.bounds.origin) || this.world;
  };
  
  HandMorph.prototype.allMorphsAtPointer = function () {
      var morphs = this.world.allChildren(),
          myself = this;
      return morphs.filter(function (m) {
          return m.isVisible &&
              m.visibleBounds().containsPoint(myself.bounds.origin);
      });
  };
  
  // HandMorph dragging and dropping:
  /*
      drag 'n' drop events, method(arg) -> receiver:
  
          prepareToBeGrabbed(handMorph) -> grabTarget
          reactToGrabOf(grabbedMorph) -> oldParent
          wantsDropOf(morphToDrop) ->  newParent
          justDropped(handMorph) -> droppedMorph
          reactToDropOf(droppedMorph, handMorph) -> newParent
  */
  
  HandMorph.prototype.dropTargetFor = function (aMorph) {
      var target = this.morphAtPointer();
      while (!target.wantsDropOf(aMorph)) {
          target = target.parent;
      }
      return target;
  };
  
  HandMorph.prototype.grab = function (aMorph) {
      var oldParent = aMorph.parent;
      if (aMorph instanceof WorldMorph) {
          return null;
      }
      if (this.children.length === 0) {
          this.world.stopEditing();
          this.grabOrigin = aMorph.situation();
          aMorph.addShadow();
          if (aMorph.prepareToBeGrabbed) {
              aMorph.prepareToBeGrabbed(this);
          }
          aMorph.cachedFullImage = aMorph.fullImageClassic();
          aMorph.cachedFullBounds = aMorph.fullBounds();
          this.add(aMorph);
          this.changed();
          if (oldParent && oldParent.reactToGrabOf) {
              oldParent.reactToGrabOf(aMorph);
          }
      }
  };
  
  HandMorph.prototype.drop = function () {
      var target, morphToDrop;
      if (this.children.length !== 0) {
          morphToDrop = this.children[0];
          target = this.dropTargetFor(morphToDrop);
          target = target.selectForEdit ? target.selectForEdit() : target;
          this.changed();
          target.add(morphToDrop);
          morphToDrop.cachedFullImage = null;
          morphToDrop.cachedFullBounds = null;
          morphToDrop.changed();
          morphToDrop.removeShadow();
          this.children = [];
          this.setExtent(new Point());
          if (morphToDrop.justDropped) {
              morphToDrop.justDropped(this);
          }
          if (target.reactToDropOf) {
              target.reactToDropOf(morphToDrop, this);
          }
      }
  };
  
  // HandMorph event dispatching:
  /*
      mouse events:
  
          mouseDownLeft
          mouseDownRight
          mouseClickLeft
          mouseClickRight
          mouseDoubleClick
          mouseEnter
          mouseLeave
          mouseEnterDragging
          mouseLeaveDragging
          mouseMove
          mouseScroll
  */
  
  HandMorph.prototype.processMouseDown = function (event) {
      var morph, actualClick;
  
      this.destroyTemporaries();
      this.contextMenuEnabled = true;
      this.morphToGrab = null;
      this.grabPosition = null;
      if (this.children.length !== 0) {
          this.drop();
          this.mouseButton = null;
      } else {
          morph = this.morphAtPointer();
          if (this.world.activeMenu) {
              if (!contains(
                      morph.allParents(),
                      this.world.activeMenu
                  )) {
                  this.world.activeMenu.destroy();
              } else {
                  clearInterval(this.touchHoldTimeout);
              }
          }
          if (this.world.activeHandle) {
              if (morph !== this.world.activeHandle) {
                  this.world.activeHandle.destroy();
              }
          }
          if (this.world.cursor) {
              if (morph !== this.world.cursor.target) {
                  this.world.stopEditing();
              }
          }
          if (!morph.mouseMove) {
              this.morphToGrab = morph.rootForGrab();
              this.grabPosition = this.bounds.origin.copy();
          }
          if (event.button === 2 || event.ctrlKey) {
              this.mouseButton = 'right';
              actualClick = 'mouseDownRight';
          } else {
              this.mouseButton = 'left';
              actualClick = 'mouseDownLeft';
          }
          while (!morph[actualClick]) {
              morph = morph.parent;
          }
          morph[actualClick](this.bounds.origin);
      }
  };
  
  HandMorph.prototype.processTouchStart = function (event) {
      var myself = this;
      MorphicPreferences.isTouchDevice = true;
      clearInterval(this.touchHoldTimeout);
      if (event.touches.length === 1) {
          this.touchHoldTimeout = setInterval( // simulate mouseRightClick
              function () {
                  myself.processMouseDown({button: 2});
                  myself.processMouseUp({button: 2});
                  event.preventDefault();
                  clearInterval(myself.touchHoldTimeout);
              },
              400
          );
          this.processMouseMove(event.touches[0]); // update my position
          this.processMouseDown({button: 0});
          event.preventDefault();
      }
  };
  
  HandMorph.prototype.processTouchMove = function (event) {
      MorphicPreferences.isTouchDevice = true;
      if (event.touches.length === 1) {
          var touch = event.touches[0];
          this.processMouseMove(touch);
          clearInterval(this.touchHoldTimeout);
      }
  };
  
  HandMorph.prototype.processTouchEnd = function (event) {
      MorphicPreferences.isTouchDevice = true;
      clearInterval(this.touchHoldTimeout);
      nop(event);
      this.processMouseUp({button: 0});
  };
  
  HandMorph.prototype.processMouseUp = function () {
      var morph = this.morphAtPointer(),
          context,
          contextMenu,
          expectedClick;
  
      this.destroyTemporaries();
      if (this.children.length !== 0) {
          this.drop();
      } else {
          if (this.mouseButton === 'left') {
              expectedClick = 'mouseClickLeft';
          } else {
              expectedClick = 'mouseClickRight';
              if (this.mouseButton && this.contextMenuEnabled) {
                  context = morph;
                  contextMenu = context.contextMenu();
                  while ((!contextMenu) &&
                          context.parent) {
                      context = context.parent;
                      contextMenu = context.contextMenu();
                  }
                  if (contextMenu) {
                      contextMenu.popUpAtHand(this.world);
                  }
              }
          }
          while (!morph[expectedClick]) {
              morph = morph.parent;
          }
          morph[expectedClick](this.bounds.origin);
      }
      this.mouseButton = null;
  };
  
  HandMorph.prototype.processDoubleClick = function () {
      var morph = this.morphAtPointer();
  
      this.destroyTemporaries();
      if (this.children.length !== 0) {
          this.drop();
      } else {
          while (morph && !morph.mouseDoubleClick) {
              morph = morph.parent;
          }
          if (morph) {
              morph.mouseDoubleClick(this.bounds.origin);
          }
      }
      this.mouseButton = null;
  };
  
  HandMorph.prototype.processMouseMove = function (event) {
      var pos,
          posInDocument = getDocumentPositionOf(this.world.worldCanvas),
          mouseOverNew,
          myself = this,
          morph,
          topMorph;
  
      pos = new Point(
          event.pageX - posInDocument.x,
          event.pageY - posInDocument.y
      );
  
      this.setPosition(pos);
  
      // determine the new mouse-over-list:
      // mouseOverNew = this.allMorphsAtPointer();
      mouseOverNew = this.morphAtPointer().allParents();
  
      if (!this.children.length && this.mouseButton) {
          topMorph = this.morphAtPointer();
          morph = topMorph.rootForGrab();
          if (topMorph.mouseMove) {
              topMorph.mouseMove(pos, this.mouseButton);
              if (this.mouseButton === 'right') {
                  this.contextMenuEnabled = false;
              }
          }
  
          // if a morph is marked for grabbing, just grab it
          if (this.mouseButton === 'left' &&
                  this.morphToGrab &&
                  (this.grabPosition.distanceTo(this.bounds.origin) >
                      MorphicPreferences.grabThreshold)) {
              this.setPosition(this.grabPosition);
              if (this.morphToGrab.isDraggable) {
                  morph = this.morphToGrab.selectForEdit ?
                          this.morphToGrab.selectForEdit() : this.morphToGrab;
                  this.grab(morph);
              } else if (this.morphToGrab.isTemplate) {
                  morph = this.morphToGrab.fullCopy();
                  morph.isTemplate = false;
                  morph.isDraggable = true;
                  if (morph.reactToTemplateCopy) {
                      morph.reactToTemplateCopy();
                  }
                  this.grab(morph);
                  this.grabOrigin = this.morphToGrab.situation();
              }
              this.setPosition(pos);
          }
      }
  
      this.mouseOverList.forEach(function (old) {
          if (!contains(mouseOverNew, old)) {
              if (old.mouseLeave) {
                  old.mouseLeave();
              }
              if (old.mouseLeaveDragging && myself.mouseButton) {
                  old.mouseLeaveDragging();
              }
          }
      });
      mouseOverNew.forEach(function (newMorph) {
          if (!contains(myself.mouseOverList, newMorph)) {
              if (newMorph.mouseEnter) {
                  newMorph.mouseEnter();
              }
              if (newMorph.mouseEnterDragging && myself.mouseButton) {
                  newMorph.mouseEnterDragging();
              }
          }
  
          // autoScrolling support:
          if (myself.children.length > 0) {
              if (newMorph instanceof ScrollFrameMorph &&
                      newMorph.enableAutoScrolling &&
                      newMorph.contents.allChildren().some(function (any) {
                          return any.wantsDropOf(myself.children[0]);
                      })
              ) {
                  if (!newMorph.bounds.insetBy(
                          MorphicPreferences.scrollBarSize * 3
                      ).containsPoint(myself.bounds.origin)) {
                      newMorph.startAutoScrolling();
                  }
              }
          }
      });
      this.mouseOverList = mouseOverNew;
  };
  
  HandMorph.prototype.processMouseScroll = function (event) {
      var morph = this.morphAtPointer();
      while (morph && !morph.mouseScroll) {
          morph = morph.parent;
      }
      if (morph) {
          morph.mouseScroll(
              (event.detail / -3) || (
                  Object.prototype.hasOwnProperty.call(
                      event,
                      'wheelDeltaY'
                  ) ?
                          event.wheelDeltaY / 120 :
                          event.wheelDelta / 120
              ),
              event.wheelDeltaX / 120 || 0
          );
      }
  };
  
  /*
      drop event:
  
          droppedImage
          droppedSVG
          droppedAudio
          droppedText
  */
  
  HandMorph.prototype.processDrop = function (event) {
  /*
      find out whether an external image or audio file was dropped
      onto the world canvas, turn it into an offscreen canvas or audio
      element and dispatch the
  
          droppedImage(canvas, name)
          droppedSVG(image, name)
          droppedAudio(audio, name)
  
      events to interested Morphs at the mouse pointer
  */
      var files = event instanceof FileList ? event
                  : event.target.files || event.dataTransfer.files,
          file,
          url = event.dataTransfer ?
                  event.dataTransfer.getData('URL') : null,
          txt = event.dataTransfer ?
                  event.dataTransfer.getData('Text/HTML') : null,
          suffix,
          src,
          target = this.morphAtPointer(),
          img = new Image(),
          canvas,
          i;
  
      function readSVG(aFile) {
          var pic = new Image(),
              frd = new FileReader();
          while (!target.droppedSVG) {
              target = target.parent;
          }
          pic.onload = function () {
              target.droppedSVG(pic, aFile.name);
          };
          frd = new FileReader();
          frd.onloadend = function (e) {
              pic.src = e.target.result;
          };
          frd.readAsDataURL(aFile);
      }
  
      function readImage(aFile) {
          var pic = new Image(),
              frd = new FileReader();
          while (!target.droppedImage) {
              target = target.parent;
          }
          pic.onload = function () {
              canvas = newCanvas(new Point(pic.width, pic.height), true);
              canvas.getContext('2d').drawImage(pic, 0, 0);
              target.droppedImage(canvas, aFile.name);
          };
          frd = new FileReader();
          frd.onloadend = function (e) {
              pic.src = e.target.result;
          };
          frd.readAsDataURL(aFile);
      }
  
      function readAudio(aFile) {
          var snd = new Audio(),
              frd = new FileReader();
          while (!target.droppedAudio) {
              target = target.parent;
          }
          frd.onloadend = function (e) {
              snd.src = e.target.result;
              target.droppedAudio(snd, aFile.name);
          };
          frd.readAsDataURL(aFile);
      }
  
      function readText(aFile) {
          var frd = new FileReader();
          while (!target.droppedText) {
              target = target.parent;
          }
          frd.onloadend = function (e) {
              target.droppedText(e.target.result, aFile.name);
          };
          frd.readAsText(aFile);
      }
  
      function readBinary(aFile) {
          var frd = new FileReader();
          while (!target.droppedBinary) {
              target = target.parent;
          }
          frd.onloadend = function (e) {
              target.droppedBinary(e.target.result, aFile.name);
          };
          frd.readAsArrayBuffer(aFile);
      }
  
      function readURL(url, callback) {
          var request = new XMLHttpRequest();
          request.open('GET', url);
          request.onreadystatechange = function () {
              if (request.readyState === 4) {
                  if (request.responseText) {
                      callback(request.responseText);
                  } else {
                      throw new Error('unable to retrieve ' + url);
                  }
              }
          };
          request.send();
      }
  
      function parseImgURL(html) {
          var iurl = '',
              idx,
              c,
              start = html.indexOf('<img src="');
          if (start === -1) {return null; }
          start += 10;
          for (idx = start; idx < html.length; idx += 1) {
              c = html[idx];
              if (c === '"') {
                  return iurl;
              }
              iurl = iurl.concat(c);
          }
          return null;
      }
  
      if (files.length > 0) {
          for (i = 0; i < files.length; i += 1) {
              file = files[i];
              if (file.type.indexOf("svg") !== -1
                      && !MorphicPreferences.rasterizeSVGs) {
                  readSVG(file);
              } else if (file.type.indexOf("image") === 0) {
                  readImage(file);
              } else if (file.type.indexOf("audio") === 0) {
                  readAudio(file);
              } else if (file.type.indexOf("text") === 0) {
                  readText(file);
              } else { // assume it's meant to be binary
                  readBinary(file);
              }
          }
      } else if (url) {
          suffix = url.slice(url.lastIndexOf('.') + 1).toLowerCase();
          if (
              contains(
                  ['gif', 'png', 'jpg', 'jpeg', 'bmp'],
                  suffix
              )
          ) {
              while (!target.droppedImage) {
                  target = target.parent;
              }
              img = new Image();
              img.onload = function () {
                  canvas = newCanvas(new Point(img.width, img.height), true);
                  canvas.getContext('2d').drawImage(img, 0, 0);
                  target.droppedImage(canvas);
              };
              img.src = url;
          } else if (suffix === 'svg' && !MorphicPreferences.rasterizeSVGs) {
              while (!target.droppedSVG) {
                  target = target.parent;
              }
              readURL(
                  url,
                  function (txt) {
                      var pic = new Image();
                      pic.onload = function () {
                          target.droppedSVG(
                              pic,
                              url.slice(
                                  url.lastIndexOf('/') + 1,
                                  url.lastIndexOf('.')
                              )
                          );
                      };
                      pic.src = 'data:image/svg+xml;utf8,' +
                          encodeURIComponent(txt);
                  }
              );
          }
      } else if (txt) {
          while (!target.droppedImage) {
              target = target.parent;
          }
          img = new Image();
          img.onload = function () {
              canvas = newCanvas(new Point(img.width, img.height), true);
              canvas.getContext('2d').drawImage(img, 0, 0);
              target.droppedImage(canvas);
          };
          src = parseImgURL(txt);
          if (src) {img.src = src; }
      }
  };
  
  // HandMorph tools
  
  HandMorph.prototype.destroyTemporaries = function () {
  /*
      temporaries are just an array of morphs which will be deleted upon
      the next mouse click, or whenever another temporary Morph decides
      that it needs to remove them. The primary purpose of temporaries is
      to display tools tips of speech bubble help.
  */
      var myself = this;
      this.temporaries.forEach(function (morph) {
          if (!(morph.isClickable
                  && morph.bounds.containsPoint(myself.position()))) {
              morph.destroy();
              myself.temporaries.splice(myself.temporaries.indexOf(morph), 1);
          }
      });
  };
  
  // WorldMorph //////////////////////////////////////////////////////////
  
  // I represent the <canvas> element
  
  // WorldMorph inherits from FrameMorph:
  
  WorldMorph.prototype = new FrameMorph();
  WorldMorph.prototype.constructor = WorldMorph;
  WorldMorph.uber = FrameMorph.prototype;
  
  // WorldMorph instance creation:
  
  function WorldMorph(aCanvas, fillPage) {
      this.init(aCanvas, fillPage);
  }
  
  // WorldMorph initialization:
  
  WorldMorph.prototype.init = function (aCanvas, fillPage) {
      WorldMorph.uber.init.call(this);
      this.color = new Color(205, 205, 205); // (130, 130, 130)
      this.alpha = 1;
      this.bounds = new Rectangle(0, 0, aCanvas.width, aCanvas.height);
      this.drawNew();
      this.isVisible = true;
      this.isDraggable = false;
      this.currentKey = null; // currently pressed key code
      this.worldCanvas = aCanvas;
      this.noticesTransparentClick = true;
  
      // additional properties:
      this.stamp = Date.now(); // reference in multi-world setups
      while (this.stamp === Date.now()) {nop(); }
      this.stamp = Date.now();
  
      this.useFillPage = fillPage;
      if (this.useFillPage === undefined) {
          this.useFillPage = true;
      }
      this.isDevMode = false;
      this.broken = [];
      this.animations = [];
      this.hand = new HandMorph(this);
      this.keyboardReceiver = null;
      this.cursor = null;
      this.lastEditedText = null;
      this.activeMenu = null;
      this.activeHandle = null;
      this.virtualKeyboard = null;
  
      this.initEventListeners();
  };
  
  // World Morph display:
  
  WorldMorph.prototype.brokenFor = function (aMorph) {
      // private
      var fb = aMorph.fullBounds();
      return this.broken.filter(function (rect) {
          return rect.intersects(fb);
      });
  };
  
  WorldMorph.prototype.fullDrawOn = function (aCanvas, aRect) {
      WorldMorph.uber.fullDrawOn.call(this, aCanvas, aRect);
      this.hand.fullDrawOn(aCanvas, aRect);
  };
  
  WorldMorph.prototype.updateBroken = function () {
      var myself = this;
      this.condenseDamages();
      this.broken.forEach(function (rect) {
          if (rect.extent().gt(new Point(0, 0))) {
              myself.fullDrawOn(myself.worldCanvas, rect);
          }
      });
      this.broken = [];
  };
  
  WorldMorph.prototype.stepAnimations = function () {
      this.animations.forEach(function (anim) {anim.step(); });
      this.animations = this.animations.filter(function (anim) {
          return anim.isActive;
      });
  };
  
  WorldMorph.prototype.condenseDamages = function () {
      // collapse clustered damaged rectangles into their unions,
      // thereby reducing the array of brokens to a manageable size
  
      function condense(src) {
          var trgt = [], hit;
          src.forEach(function (rect) {
              hit = detect(
                  trgt,
                  function (each) {return each.isNearTo(rect, 20); }
              );
              if (hit) {
                  hit.mergeWith(rect);
              } else {
                  trgt.push(rect);
              }
          });
          return trgt;
      }
  
      var again = true, size = this.broken.length;
      while (again) {
          this.broken = condense(this.broken);
          again = (this.broken.length < size);
          size = this.broken.length;
      }
  };
  
  WorldMorph.prototype.doOneCycle = function () {
      this.stepFrame();
      this.stepAnimations();
      this.updateBroken();
  };
  
  WorldMorph.prototype.fillPage = function () {
      var clientHeight = window.innerHeight,
          clientWidth = window.innerWidth,
          myself = this;
  
      this.worldCanvas.style.position = "absolute";
      this.worldCanvas.style.left = "0px";
      this.worldCanvas.style.right = "0px";
      this.worldCanvas.style.width = "100%";
      this.worldCanvas.style.height = "100%";
  
      if (document.documentElement.scrollTop) {
          // scrolled down b/c of viewport scaling
          clientHeight = document.documentElement.clientHeight;
      }
      if (document.documentElement.scrollLeft) {
          // scrolled left b/c of viewport scaling
          clientWidth = document.documentElement.clientWidth;
      }
      if (this.worldCanvas.width !== clientWidth) {
          this.worldCanvas.width = clientWidth;
          this.setWidth(clientWidth);
      }
      if (this.worldCanvas.height !== clientHeight) {
          this.worldCanvas.height = clientHeight;
          this.setHeight(clientHeight);
      }
      this.children.forEach(function (child) {
          if (child.reactToWorldResize) {
              child.reactToWorldResize(myself.bounds.copy());
          }
      });
  };
  
  // WorldMorph global pixel access:
  
  WorldMorph.prototype.getGlobalPixelColor = function (point) {
      // answer the color at the given point.
  
  /*
      // original method, now deprecated as of 4/4/2017 because Chrome
      // "taints" the on-screen canvas as soon as its image data is
      // requested, significantly slowing down subsequent blittings
  
      var dta = this.worldCanvas.getContext('2d').getImageData(
          point.x,
          point.y,
          1,
          1
      ).data;
      return new Color(dta[0], dta[1], dta[2]);
  */
  
      var clr = this.hand.morphAtPointer().getPixelColor(this.hand.position());
      // IMPORTANT:
      // all callers of getGlobalPixelColor should make provisions for retina
      // display support, which gets null-pixels interlaced with non-null ones:
      // if (!clr.a) {/* ignore */ }
      return clr;
  };
  
  // WorldMorph events:
  
  WorldMorph.prototype.initVirtualKeyboard = function () {
      var myself = this;
  
      if (this.virtualKeyboard) {
          document.body.removeChild(this.virtualKeyboard);
          this.virtualKeyboard = null;
      }
      if (!MorphicPreferences.isTouchDevice
              || !MorphicPreferences.useVirtualKeyboard) {
          return;
      }
      this.virtualKeyboard = document.createElement("input");
      this.virtualKeyboard.type = "text";
      this.virtualKeyboard.style.color = "transparent";
      this.virtualKeyboard.style.backgroundColor = "transparent";
      this.virtualKeyboard.style.border = "none";
      this.virtualKeyboard.style.outline = "none";
      this.virtualKeyboard.style.position = "absolute";
      this.virtualKeyboard.style.top = "0px";
      this.virtualKeyboard.style.left = "0px";
      this.virtualKeyboard.style.width = "0px";
      this.virtualKeyboard.style.height = "0px";
      this.virtualKeyboard.autocapitalize = "none"; // iOS specific
      document.body.appendChild(this.virtualKeyboard);
  
      this.virtualKeyboard.addEventListener(
          "keydown",
          function (event) {
              // remember the keyCode in the world's currentKey property
              myself.currentKey = event.keyCode;
              if (myself.keyboardReceiver) {
                  myself.keyboardReceiver.processKeyDown(event);
              }
              // supress backspace override
              if (event.keyCode === 8) {
                  event.preventDefault();
              }
              // supress tab override and make sure tab gets
              // received by all browsers
              if (event.keyCode === 9) {
                  if (myself.keyboardReceiver) {
                      myself.keyboardReceiver.processKeyPress(event);
                  }
                  event.preventDefault();
              }
          },
          false
      );
  
      this.virtualKeyboard.addEventListener(
          "keyup",
          function (event) {
              // flush the world's currentKey property
              myself.currentKey = null;
              // dispatch to keyboard receiver
              if (myself.keyboardReceiver) {
                  if (myself.keyboardReceiver.processKeyUp) {
                      myself.keyboardReceiver.processKeyUp(event);
                  }
              }
              event.preventDefault();
          },
          false
      );
  
      this.virtualKeyboard.addEventListener(
          "keypress",
          function (event) {
              if (myself.keyboardReceiver) {
                  myself.keyboardReceiver.processKeyPress(event);
              }
              event.preventDefault();
          },
          false
      );
  };
  
  WorldMorph.prototype.initEventListeners = function () {
      var canvas = this.worldCanvas, myself = this;
  
      if (myself.useFillPage) {
          myself.fillPage();
      } else {
          this.changed();
      }
  
      canvas.addEventListener(
          "mousedown",
          function (event) {
              event.preventDefault();
              canvas.focus();
              myself.hand.processMouseDown(event);
          },
          false
      );
  
      canvas.addEventListener(
          "touchstart",
          function (event) {
              myself.hand.processTouchStart(event);
          },
          false
      );
  
      canvas.addEventListener(
          "mouseup",
          function (event) {
              event.preventDefault();
              myself.hand.processMouseUp(event);
          },
          false
      );
  
      canvas.addEventListener(
          "dblclick",
          function (event) {
              event.preventDefault();
              myself.hand.processDoubleClick(event);
          },
          false
      );
  
      canvas.addEventListener(
          "touchend",
          function (event) {
              myself.hand.processTouchEnd(event);
          },
          false
      );
  
      canvas.addEventListener(
          "mousemove",
          function (event) {
              myself.hand.processMouseMove(event);
          },
          false
      );
  
      canvas.addEventListener(
          "touchmove",
          function (event) {
              myself.hand.processTouchMove(event);
          },
          false
      );
  
      canvas.addEventListener(
          "contextmenu",
          function (event) {
              // suppress context menu for Mac-Firefox
              event.preventDefault();
          },
          false
      );
  
      canvas.addEventListener(
          "keydown",
          function (event) {
              // remember the keyCode in the world's currentKey property
              myself.currentKey = event.keyCode;
              if (myself.keyboardReceiver) {
                  myself.keyboardReceiver.processKeyDown(event);
              }
              // supress backspace override
              if (event.keyCode === 8) {
                  event.preventDefault();
              }
              // supress tab override and make sure tab gets
              // received by all browsers
              if (event.keyCode === 9) {
                  if (myself.keyboardReceiver) {
                      myself.keyboardReceiver.processKeyPress(event);
                  }
                  event.preventDefault();
              }
              if ((event.ctrlKey && (!event.altKey) || event.metaKey) &&
                      (event.keyCode !== 86)) { // allow pasting-in
                  event.preventDefault();
              }
          },
          false
      );
  
      canvas.addEventListener(
          "keyup",
          function (event) {
              // flush the world's currentKey property
              myself.currentKey = null;
              // dispatch to keyboard receiver
              if (myself.keyboardReceiver) {
                  if (myself.keyboardReceiver.processKeyUp) {
                      myself.keyboardReceiver.processKeyUp(event);
                  }
              }
              event.preventDefault();
          },
          false
      );
  
      canvas.addEventListener(
          "keypress",
          function (event) {
              if (myself.keyboardReceiver) {
                  myself.keyboardReceiver.processKeyPress(event);
              }
              event.preventDefault();
          },
          false
      );
  
      canvas.addEventListener( // Safari, Chrome
          "mousewheel",
          function (event) {
              myself.hand.processMouseScroll(event);
              event.preventDefault();
          },
          false
      );
      canvas.addEventListener( // Firefox
          "DOMMouseScroll",
          function (event) {
              myself.hand.processMouseScroll(event);
              event.preventDefault();
          },
          false
      );
  
      document.body.addEventListener(
          "paste",
          function (event) {
              var txt = event.clipboardData.getData("Text");
              if (txt && myself.cursor) {
                  myself.cursor.insert(txt);
              }
          },
          false
      );
  
      window.addEventListener(
          "dragover",
          function (event) {
              event.preventDefault();
          },
          false
      );
      window.addEventListener(
          "drop",
          function (event) {
              myself.hand.processDrop(event);
              event.preventDefault();
          },
          false
      );
  
      window.addEventListener(
          "resize",
          function () {
              if (myself.useFillPage) {
                  myself.fillPage();
              }
          },
          false
      );
  
      window.onbeforeunload = function (evt) {
          var e = evt || window.event,
              msg = "Are you sure you want to leave?";
          // For IE and Firefox
          if (e) {
              e.returnValue = msg;
          }
          // For Safari / chrome
          return msg;
      };
  };
  
  WorldMorph.prototype.mouseDownLeft = nop;
  
  WorldMorph.prototype.mouseClickLeft = nop;
  
  WorldMorph.prototype.mouseDownRight = nop;
  
  WorldMorph.prototype.mouseClickRight = nop;
  
  WorldMorph.prototype.wantsDropOf = function () {
      // allow handle drops if any drops are allowed
      return this.acceptsDrops;
  };
  
  WorldMorph.prototype.droppedImage = function () {
      return null;
  };
  
  WorldMorph.prototype.droppedSVG = function () {
      return null;
  };
  
  // WorldMorph text field tabbing:
  
  WorldMorph.prototype.nextTab = function (editField) {
      var next = this.nextEntryField(editField);
      if (next) {
          editField.clearSelection();
          next.selectAll();
          next.edit();
      }
  };
  
  WorldMorph.prototype.previousTab = function (editField) {
      var prev = this.previousEntryField(editField);
      if (prev) {
          editField.clearSelection();
          prev.selectAll();
          prev.edit();
      }
  };
  
  // WorldMorph menu:
  
  WorldMorph.prototype.contextMenu = function () {
      var menu;
  
      if (this.isDevMode) {
          menu = new MenuMorph(this, this.constructor.name ||
              this.constructor.toString().split(' ')[1].split('(')[0]);
      } else {
          menu = new MenuMorph(this, 'Morphic');
      }
      if (this.isDevMode) {
          menu.addItem("demo...", 'userCreateMorph', 'sample morphs');
          menu.addLine();
          menu.addItem("hide all...", 'hideAll');
          menu.addItem("show all...", 'showAllHiddens');
          menu.addItem(
              "move all inside...",
              'keepAllSubmorphsWithin',
              'keep all submorphs\nwithin and visible'
          );
          menu.addItem(
              "inspect...",
              'inspect',
              'open a window on\nall properties'
          );
          menu.addItem(
              "screenshot...",
              function () {
                  window.open(this.fullImageClassic().toDataURL());
              },
              'open a new window\nwith a picture of this morph'
          );
          menu.addLine();
          menu.addItem(
              "restore display",
              'changed',
              'redraw the\nscreen once'
          );
          menu.addItem(
              "fill page...",
              'fillPage',
              'let the World automatically\nadjust to browser resizing'
          );
          if (useBlurredShadows) {
              menu.addItem(
                  "sharp shadows...",
                  'toggleBlurredShadows',
                  'sharp drop shadows\nuse for old browsers'
              );
          } else {
              menu.addItem(
                  "blurred shadows...",
                  'toggleBlurredShadows',
                  'blurry shades,\n use for new browsers'
              );
          }
          menu.addItem(
              "color...",
              function () {
                  this.pickColor(
                      menu.title + localize('\ncolor:'),
                      this.setColor,
                      this,
                      this.color
                  );
              },
              'choose the World\'s\nbackground color'
          );
          if (MorphicPreferences === standardSettings) {
              menu.addItem(
                  "touch screen settings",
                  'togglePreferences',
                  'bigger menu fonts\nand sliders'
              );
          } else {
              menu.addItem(
                  "standard settings",
                  'togglePreferences',
                  'smaller menu fonts\nand sliders'
              );
          }
          menu.addLine();
      }
      if (this.isDevMode) {
          menu.addItem(
              "user mode...",
              'toggleDevMode',
              'disable developers\'\ncontext menus'
          );
      } else {
          menu.addItem("development mode...", 'toggleDevMode');
      }
      menu.addItem("about morphic.js...", 'about');
      return menu;
  };
  
  WorldMorph.prototype.userCreateMorph = function () {
      var myself = this, menu, newMorph;
  
      function create(aMorph) {
          aMorph.isDraggable = true;
          aMorph.pickUp(myself);
      }
  
      menu = new MenuMorph(this, 'make a morph');
      menu.addItem('rectangle', function () {
          create(new Morph());
      });
      menu.addItem('box', function () {
          create(new BoxMorph());
      });
      menu.addItem('circle box', function () {
          create(new CircleBoxMorph());
      });
      menu.addLine();
      menu.addItem('slider', function () {
          create(new SliderMorph());
      });
      menu.addItem('frame', function () {
          newMorph = new FrameMorph();
          newMorph.setExtent(new Point(350, 250));
          create(newMorph);
      });
      menu.addItem('scroll frame', function () {
          newMorph = new ScrollFrameMorph();
          newMorph.contents.acceptsDrops = true;
          newMorph.contents.adjustBounds();
          newMorph.setExtent(new Point(350, 250));
          create(newMorph);
      });
      menu.addItem('handle', function () {
          create(new HandleMorph());
      });
      menu.addLine();
      menu.addItem('string', function () {
          newMorph = new StringMorph('Hello, World!');
          newMorph.isEditable = true;
          create(newMorph);
      });
      menu.addItem('text', function () {
          newMorph = new TextMorph(
              "Ich wei\u00DF nicht, was soll es bedeuten, dass ich so " +
                  "traurig bin, ein M\u00E4rchen aus uralten Zeiten, das " +
                  "kommt mir nicht aus dem Sinn. Die Luft ist k\u00FChl " +
                  "und es dunkelt, und ruhig flie\u00DFt der Rhein; der " +
                  "Gipfel des Berges funkelt im Abendsonnenschein. " +
                  "Die sch\u00F6nste Jungfrau sitzet dort oben wunderbar, " +
                  "ihr gold'nes Geschmeide blitzet, sie k\u00E4mmt ihr " +
                  "goldenes Haar, sie k\u00E4mmt es mit goldenem Kamme, " +
                  "und singt ein Lied dabei; das hat eine wundersame, " +
                  "gewalt'ge Melodei. Den Schiffer im kleinen " +
                  "Schiffe, ergreift es mit wildem Weh; er schaut " +
                  "nicht die Felsenriffe, er schaut nur hinauf in " +
                  "die H\u00F6h'. Ich glaube, die Wellen verschlingen " +
                  "am Ende Schiffer und Kahn, und das hat mit ihrem " +
                  "Singen, die Loreley getan."
          );
          newMorph.isEditable = true;
          newMorph.maxWidth = 300;
          newMorph.drawNew();
          create(newMorph);
      });
      menu.addItem('speech bubble', function () {
          newMorph = new SpeechBubbleMorph('Hello, World!');
          create(newMorph);
      });
      menu.addLine();
      menu.addItem('gray scale palette', function () {
          create(new GrayPaletteMorph());
      });
      menu.addItem('color palette', function () {
          create(new ColorPaletteMorph());
      });
      menu.addItem('color picker', function () {
          create(new ColorPickerMorph());
      });
      menu.addLine();
      menu.addItem('sensor demo', function () {
          newMorph = new MouseSensorMorph();
          newMorph.setColor(new Color(230, 200, 100));
          newMorph.edge = 35;
          newMorph.border = 15;
          newMorph.borderColor = new Color(200, 100, 50);
          newMorph.alpha = 0.2;
          newMorph.setExtent(new Point(100, 100));
          create(newMorph);
      });
      menu.addItem('animation demo', function () {
          var foo, bar, baz, garply, fred;
  
          foo = new BouncerMorph();
          foo.setPosition(new Point(50, 20));
          foo.setExtent(new Point(300, 200));
          foo.alpha = 0.9;
          foo.speed = 3;
  
          bar = new BouncerMorph();
          bar.setColor(new Color(50, 50, 50));
          bar.setPosition(new Point(80, 80));
          bar.setExtent(new Point(80, 250));
          bar.type = 'horizontal';
          bar.direction = 'right';
          bar.alpha = 0.9;
          bar.speed = 5;
  
          baz = new BouncerMorph();
          baz.setColor(new Color(20, 20, 20));
          baz.setPosition(new Point(90, 140));
          baz.setExtent(new Point(40, 30));
          baz.type = 'horizontal';
          baz.direction = 'right';
          baz.speed = 3;
  
          garply = new BouncerMorph();
          garply.setColor(new Color(200, 20, 20));
          garply.setPosition(new Point(90, 140));
          garply.setExtent(new Point(20, 20));
          garply.type = 'vertical';
          garply.direction = 'up';
          garply.speed = 8;
  
          fred = new BouncerMorph();
          fred.setColor(new Color(20, 200, 20));
          fred.setPosition(new Point(120, 140));
          fred.setExtent(new Point(20, 20));
          fred.type = 'vertical';
          fred.direction = 'down';
          fred.speed = 4;
  
          bar.add(garply);
          bar.add(baz);
          foo.add(fred);
          foo.add(bar);
  
          create(foo);
      });
      menu.addItem('pen', function () {
          create(new PenMorph());
      });
      if (myself.customMorphs) {
          menu.addLine();
          myself.customMorphs().forEach(function (morph) {
              menu.addItem(morph.toString(), function () {
                  create(morph);
              });
          });
      }
      menu.popUpAtHand(this);
  };
  
  WorldMorph.prototype.toggleDevMode = function () {
      this.isDevMode = !this.isDevMode;
  };
  
  WorldMorph.prototype.hideAll = function () {
      this.children.forEach(function (child) {
          child.hide();
      });
  };
  
  WorldMorph.prototype.showAllHiddens = function () {
      this.forAllChildren(function (child) {
          if (!child.isVisible) {
              child.show();
          }
      });
  };
  
  WorldMorph.prototype.about = function () {
      var versions = '', module;
  
      for (module in modules) {
          if (Object.prototype.hasOwnProperty.call(modules, module)) {
              versions += ('\n' + module + ' (' + modules[module] + ')');
          }
      }
      if (versions !== '') {
          versions = '\n\nmodules:\n\n' +
              'morphic (' + morphicVersion + ')' +
              versions;
      }
  
      this.inform(
          'morphic.js\n\n' +
              'a lively Web GUI\ninspired by Squeak\n' +
              morphicVersion +
              '\n\nwritten by Jens M\u00F6nig\njens@moenig.org' +
              versions
      );
  };
  
  WorldMorph.prototype.edit = function (aStringOrTextMorph) {
      var pos = getDocumentPositionOf(this.worldCanvas);
  
      if (!aStringOrTextMorph.isEditable) {
          return null;
      }
      if (this.cursor) {
          this.cursor.destroy();
      }
      this.cursor = new CursorMorph(aStringOrTextMorph);
      aStringOrTextMorph.parent.add(this.cursor);
      this.keyboardReceiver = this.cursor;
  
      this.initVirtualKeyboard();
      if (MorphicPreferences.isTouchDevice
              && MorphicPreferences.useVirtualKeyboard) {
          this.virtualKeyboard.style.top = this.cursor.top() + pos.y + "px";
          this.virtualKeyboard.style.left = this.cursor.left() + pos.x + "px";
          this.virtualKeyboard.focus();
      }
  
      if (MorphicPreferences.useSliderForInput) {
          if (!aStringOrTextMorph.parentThatIsA(MenuMorph)) {
              this.slide(aStringOrTextMorph);
          }
      }
  
      if (this.lastEditedText !== aStringOrTextMorph) {
          aStringOrTextMorph.escalateEvent('freshTextEdit', aStringOrTextMorph);
      }
      this.lastEditedText = aStringOrTextMorph;
  };
  
  WorldMorph.prototype.slide = function (aStringOrTextMorph) {
      // display a slider for numeric text entries
      var val = parseFloat(aStringOrTextMorph.text),
          menu,
          slider;
  
      if (isNaN(val)) {
          val = 0;
      }
      menu = new MenuMorph();
      slider = new SliderMorph(
          val - 25,
          val + 25,
          val,
          10,
          'horizontal'
      );
      slider.alpha = 1;
      slider.color = new Color(225, 225, 225);
      slider.button.color = menu.borderColor;
      slider.button.highlightColor = slider.button.color.copy();
      slider.button.highlightColor.b += 100;
      slider.button.pressColor = slider.button.color.copy();
      slider.button.pressColor.b += 150;
      slider.silentSetHeight(MorphicPreferences.scrollBarSize);
      slider.silentSetWidth(MorphicPreferences.menuFontSize * 10);
      slider.drawNew();
      slider.action = function (num) {
          aStringOrTextMorph.changed();
          aStringOrTextMorph.text = Math.round(num).toString();
          aStringOrTextMorph.drawNew();
          aStringOrTextMorph.changed();
          aStringOrTextMorph.escalateEvent(
              'reactToSliderEdit',
              aStringOrTextMorph
          );
      };
      menu.items.push(slider);
      menu.popup(this, aStringOrTextMorph.bottomLeft().add(new Point(0, 5)));
  };
  
  WorldMorph.prototype.stopEditing = function () {
      if (this.cursor) {
          this.cursor.target.escalateEvent('reactToEdit', this.cursor.target);
          this.cursor.target.clearSelection();
          this.cursor.destroy();
          this.cursor = null;
      }
      if (this.keyboardReceiver && this.keyboardReceiver.stopEditing) {
      	this.keyboardReceiver.stopEditing();
      }
      this.keyboardReceiver = null;
      if (this.virtualKeyboard) {
          this.virtualKeyboard.blur();
          document.body.removeChild(this.virtualKeyboard);
          this.virtualKeyboard = null;
      }
      this.lastEditedText = null;
      this.worldCanvas.focus();
  };
  
  WorldMorph.prototype.toggleBlurredShadows = function () {
      useBlurredShadows = !useBlurredShadows;
  };
  
  WorldMorph.prototype.togglePreferences = function () {
      if (MorphicPreferences === standardSettings) {
          MorphicPreferences = touchScreenSettings;
      } else {
          MorphicPreferences = standardSettings;
      }
  };
  