When adding a child to a parent, it's parent is set before it's scene. This might result in wrong assumption in a parent property listener (or any other property that's invalidated by parent invalidation like localToSceneProperty, etc...) that the node has already a scene/subscene. I think we should avoid such middle states in our listeners by postponing the notifications until all of the related properties are set.

I think there are more places in scenegraph or controls with similar situation: multiple properties that need to be changed atomically in order to keep the invariant.