Initialization : I had a complete Scene.addChild(WidgetP) and WidgetP.addChild(WidgetC) structure, and added a defaultMoveAction to WidgetP. I override the isHitAt method of WidgetP such that it will return true if any of its children.isHitAt returns true.

Problem : I tried to drag WidgetP, but it won’t move. Hmm there must be something wrong with my code, so I switch back to Netbeans but it seems that there’s nothing wrong. So I switch back to my app and WidgetC has been moved. Ghost. I move it again, it stands still. I zoom the Scene out, it moves.

I tried to listen the event and put a SceneListener on my TopComponent. Indeed, no event is fired while I drag the widget.

The thing is, if I drag WidgetC far enough to trigger the scrollbar to appear, it is rendered correctly under my cursor.

Culprit : WidgetP extends LayerWidget.

Solution : Changing the declaration of superclass from LayerWidget to Widget solves the problem.

Lesson learned : LayerWidget.isRepaintRequiredForRevalidating always returns false. Next time, I will remind myself not to type extends LayerWidget and use Widget instead.