anchor.diff:      _pendingToDrag();
       
       // send over event
  -    _dragOverStreamController.add(new DragEvent(this, event.currentTarget, event));
  +    _dragOverStreamController.add(new DragEvent(this, _currentTarget, event, event.currentTarget));
     }
     void _mouseOutHandler(MouseEvent event) {
       // only respond to this event when the element we're going to is
  
positive.code:     _pendingToDrag();
      
      // send out event
      _dragOutStreamController.add(new DragEvent(this, event.currentTarget, event));
    }
    void _mouseMoveHandler(MouseEvent event) {
      // do actual start in case we were pending before
  
negative.code:   Element element;
    /// The [MouseEvent] that instigated the drag handler event
    MouseEvent mouseEvent;
    /// For out events, the [Element] being dragged out of
    /// For over events, the [Element] being dragged over
    Element other;
    DragEvent(DragHandler this.dragHandler, Element this.element, MouseEvent this.mouseEvent, [Element this.other]);
  }
  
  // TODO make universal enable/disable flag
  