(In reply to comment #5)
> It seems to only show up in apps that use OpenGL and only after a
> suspend/resume cycle.

If it only happens in OpenGL apps, that indicates a problem in the 3D rendering
pipeline.

> I'm not using a desktop compositor, so i never see it affect the whole screen
> like Rafał's screenshots.

Actually, my assumption from Rafał's description was that he's only seeing the
problem on one of several connected displays at a time, which would indicate a
problem in the display pipeline instead (assuming all displays are showing the
same contents or are all updating their contents while the problem occurs).
Rafał, is my assumption correct?