To reproduce

1. Create a QWidget
2. Maximize it
3. call resize() with a size smaller than the maximized size (e.g. 400x400)

Afterwards the widget will only be painted in the new size(400x400) however the window will still be maximized, the extra space around that area displays the content behind the window. New paint events will report a region of 400x400.

I expected the window to remain maximized and the resize() to have no effect.

Attached, a minimal example that maximizes a QWidget and then resizes it - prints all paint events. Also a screenshot of the issue.