extended gui problem on maximized view

Start a video and maximize the screen but not with fullscreen/doubleclick but by using maximize in the title bar (top right).

Turning on Extended GUI causes some transparancy/corruption effect and unusable GUI (also with openGL and no overlay). This problem does not occur when Extended GUI was turned on before the maximize.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information