anchor.diff:  
     int getTargetDimension() {
       final style = _target.getComputedStyle();
  -    return int.parse((_dimension == _DIM_HEIGHT) ? style.height : style.width);
  +    final dimStr = (_dimension == _DIM_HEIGHT) ? style.height : style.width;
  +    final dim = int.parse(dimStr.replaceFirst('px', ''));
  +    return dim;
     }
   
     void setTargetDimension(int dimension) {
  
positive.code:   void dragStart(MouseEvent e) {
      update();
      classes.add('active');
      _size = getTargetDimension();
    }
  
    void drag(MouseEvent e) {
      if (!locked) {
        final delta = _horizontal ? e.movement.y : e.movement.x;
        setTargetDimension(_size + (_isNext ? -delta : delta));
      }
    }
  
    void dragEnd(MouseEvent e) {
      classes.remove('active');
    }
  }
  
negative.code:   bool _isNext;
    bool _horizontal;
    int _dimension;
    bool _isDragged = false;
  
    SparkSplitter.created() : super.created() {
      onMouseDown.listen(dragStart);
      onMouseMove.listen(drag);
      onMouseUp.listen(dragEnd);
      // TODO(sergeygs): Switch to using onDrag* instead of onMouse* once support
      // has been added to Polymer Dart.
      //onDragStart.listen(dragStart);
      //onDrag.listen(drag);
      //onDragEnd.listen(dragEnd);
  
      directionChanged();
    }
  