This is not the case for a freshly booted VM, but after running a few OpenGL programs for a while, this will eventually manifest itself. The always-on-top status of often, but not always, accompanied by colours in glxgears being incorrect (currently they are washed out--the red gear is magenta on my screen, sadly I can't take a screenshot of this as gnome-screenshot just produces a black image).
-- Sam Morris <s...@robots.org.uk> -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org