I wrote the earlier thing wrongly - it's not the height/width that's wrong. It's the window x that is incorrect, due to the decorator. So the problem either lives in the decorator itself or the decorator plugin. The buggy maximized windows have correct width, but the x parameter in some moments of drawing is wrongly shifted by the width of the decorator titlebar.
I wrote the earlier thing wrongly - it's not the height/width that's wrong. It's the window x that is incorrect, due to the decorator. So the problem either lives in the decorator itself or the decorator plugin. The buggy maximized windows have correct width, but the x parameter in some moments of drawing is wrongly shifted by the width of the decorator titlebar.