anchor.diff:     "This class implements a pane that supports the CLIM graphics,
       extended input and output, and output recording protocols."))
   
  -(defmethod compose-space ((pane clim-stream-pane) &key width height)
  -  (declare (ignore width height))
  -  (make-space-requirement :width 300 :height 300))
  -
   (defmethod window-clear ((pane clim-stream-pane))
     (let ((output-history (pane-output-history pane)))
       (with-bounding-rectangle* (left top right bottom) output-history
  
positive.code: 
  (defmethod allocate-space ((pane scroller-pane) width height)
    (with-slots (viewport vscrollbar hscrollbar) pane
      (when viewport
        (setf (sheet-transformation viewport)
  	(make-translation-transformation (if vscrollbar *scrollbar-thickness* 0) 0))
        (allocate-space viewport
  		      (if vscrollbar (- width *scrollbar-thickness*) width)
  		      (if hscrollbar (- height *scrollbar-thickness*) height)))
      (when vscrollbar
        (setf (sheet-transformation vscrollbar)
  	(make-translation-transformation 0 0))
        (allocate-space vscrollbar
  		      *scrollbar-thickness*
  		      (if hscrollbar (- height *scrollbar-thickness*) height)))
      (when hscrollbar
        (move-sheet hscrollbar
                    (if vscrollbar
                        *scrollbar-thickness*
                      0)
                    (- height *scrollbar-thickness*))
        (allocate-space hscrollbar
  		      (if vscrollbar (- width *scrollbar-thickness*) width)
  		      *scrollbar-thickness*))
      ;;
      (scroller-pane/update-scroll-bars pane)
      ))
  
  ;;;; Initialization
  
  
negative.code:                                                   (- (bounding-rectangle-max-y (sheet-region scrollee))
                                                       (bounding-rectangle-height (sheet-region viewport)))
                                                    (bounding-rectangle-min-y (sheet-region scrollee)))
                (scroll-bar-thumb-size vscrollbar) (bounding-rectangle-height (sheet-region viewport))
                (gadget-value vscrollbar :invoke-callback nil)
                (- (nth-value 1 (transform-position (sheet-transformation scrollee) 0 0)))
                )))))
  
  (defmethod initialize-instance :after ((pane scroller-pane) &key contents &allow-other-keys)
    (sheet-adopt-child pane (first contents))
  