Comment 0 for bug 1493676

mir_proving_server background is black (instead of grey) on Android when using overlays. Also if you have a mouse working, the background flickers when you move it.

This appears to be quite a predictable bug. Since overlay support was fixed in Mir 0.15 (bug 1474231), the issue only just became visible. It seems to be a simple missing feature -- we have no way to tell the compositor that the background requires OpenGL to be painted. It just assumes when there are no surfaces that it can overlay everything, making the background black. However mir_proving_server requires that overlays be avoided in that case because OpenGL is needed to paint the background.