anchor.diff:    ScrollBar _hbar, _vbar;
     Point<num> _viewport;
   
  -  ScrollView(): super() {
  +  ScrollView() : super() {
       _hbar = new ScrollBar(orientation: Orientation.HORIZONTAL)..visible = false;
       addChild(_hbar);
       _vbar = new ScrollBar(orientation: Orientation.VERTICAL)..visible = false;
  
positive.code:     }
    }
  
    void _stopScrolling() {
      _showScrollBars();
      stage.removeEventListener(TouchEvent.TOUCH_MOVE, _stageMoveHandler);
      stage.removeEventListener(TouchEvent.TOUCH_END, _stageUpHandler);
  
negative.code:   }
  
    void _stageMoveHandler(e) {
      mouseChildren = false;
      var delta = new Point(e.stageX, e.stageY) - _lastPos;
      scrollTo(_content.x + delta.x, _content.y + delta.y);
      _lastPos.setTo(e.stageX, e.stageY);
    }
  
    void _stageUpHandler(Event e) {
      _stopDrag();
    }
  
    void _resizeHandler(Event event) {
  