I have the following issue:

1 Outside pane, inside the following components in the following sequence:
...(1) Canvas (0,0,100,100)
...(2) Button (0,0,100,30)
...(3) Canvas (90,90,100,100)
...(4) Button (90,90,100,30)
So there is an overlapping area of 10x10 between (1),(2) and (3),(4).

When moving with the mouse over (4)-Button then the (1)-Canvas is drawn over the (2)-Button - which is not correct.

It seems to me like a rendering-sequence/dependency-issue: moving the mouse re-renders (4)-Button, triggering a re-rendering of (1)-Canvas because of overlapping, but (2)-Button seems not to be re-rendered.

I attached a demo program showing the effect.