I have this very weird glitch with Gnome, running on Xorg. I can move my mouse off the right hand edge of the screen, and the entire gnome UI starts to scroll over the the left, giving me a glitchy mess on the right hand side of the screen. The screenshot doesn't really do it justice, because it just became transparent instead, but the transparent region where the terminal is should be off screen.
Hope I have explained that well, has anyone else hit that? I wonder if its due to multiple monitors, or non-aligned monitors?
