anchor.diff:     * Fired when the user ends the dragging. 
      * 
      * Is also fired when the user clicks the 'esc'-key or the window loses focus. 
  -   * For those two cases, the mouse positions of [DragEvent] will be null.
      */
     Stream<DragEvent> get onDragEnd => _dragDetector.onDragEnd;
     
  
positive.code:         disableMouse: disableMouse, 
          handle: handle,
          cancel: cancel,
          draggingClassElement: draggingClassSwiper, 
          draggingClassBody: draggingClassBody);
      
      // Swiping is only done horizontally.
      _dragDetector.horizontalOnly = true;
      
      // Listen for drag events.
      _subs.add(_dragDetector.onDragStart.listen(_handleDragStart));
  
negative.code:    * If swipe duration is less than [durationThreshold] (in ms), a swipe is  
     * detected (regardless of swipe distance).
     * 
     * The [draggingClass] is the css class set to the [swiperElement] 
     * while a user is dragging. If set to null, no such css class is added.
     * 
     * The [draggingClassBody] is the css class set to the html body tag
     * while a user is dragging. If set to null, no such css class is added.
     */
    Swiper(Element swiperElement, 
        { int startIndex: 0, 
          int speed: 300, 
          bool autoWidth: true, 
          double autoHeightRatio: null, 
          int distanceThreshold: 20,
          int durationThreshold: 250,
          bool disableTouch: false, 
          bool disableMouse: false,
          String handle: null, 
          String cancel: 'input, textarea, button, select, option',
          String draggingClass: 'swiper-dragging',
          String draggingClassBody: 'swiper-drag-occurring'})
          
        : this._swiperElement = swiperElement,
          this._speed = speed, 
          this._autoWidth = autoWidth,
          this._autoHeightRatio = autoHeightRatio,
          this._distanceThreshold = distanceThreshold, 
          this._durationThreshold = durationThreshold {
      
      _log.fine('Initializing Swiper');
      
  