anchor.diff:    }
   
     void _handleEvent(sky.Event e) {
  -    sky.EventListener listener = listeners[e.type];
  +    EventListener listener = listeners[e.type];
       if (listener != null) {
         listener(e);
       }
  
positive.code:     PointerEventListener onPointerDown,
      PointerEventListener onPointerMove,
      PointerEventListener onPointerUp,
      Map<String, sky.EventListener> custom
    }) {
      var listeners = custom != null ?
          new HashMap<String, sky.EventListener>.from(custom) :
          new HashMap<String, sky.EventListener>();
  
      if (onWheel != null)
        listeners['wheel'] = onWheel;
  
negative.code:     PointerEventListener onPointerDown,
      PointerEventListener onPointerMove,
      PointerEventListener onPointerUp,
      Map<String, EventListener> custom
    }) : listeners = _createListeners(
           onWheel: onWheel,
           onGestureFlingCancel: onGestureFlingCancel,
  