Every so often my Ubuntu install goes a little weird. When I mouse-over any window decorations, or interface elements in some apps, they vanish. The window itself is still visible, just empty. I can't take a screenshot, because if I load a screenshot app I can't see what to click to grab a screenshot, so here's a photo instead.
I don't know what's causing this. The interface elements are all still click-able; I can maximize windows, open items ... everything, if I click in the right place. I just can't see what I'm clicking.
The global menu bar loads fine, and I see all menu options in the bar, but not in the drop-downs. My dropbox icon is visible and functional, and the drop-down menu loads on click ... but it's empty.
What could be causing this, and how can I get back to a working interface without restarting the machine or logging out?
I'm using 13.04, Compiz/Unity with a GeForce GT 640 card with the Nouveau driver.
You should try installing the proprietary driver if it doesn't bother you. To install it directly execute the .run file. You may also try Unity 2D, which doesn't use hardware acceleration. If changing the driver doesn't fix it but using Unity 2D does, this indicates a possible issue with the videocard hardware.
To restart the unity shell (and clean up the garbage without logging off and back on), use Alt+F2 to open the run dialog, type (blindly if the problem is that bad)
unity --replaceand Enter. The current unity session is replaced with a new, clean one.Other people using other compositing shells (like Gnome 3) could alt+F2 and type r. Unity just picks the first executable to begin with r instead of doing a shell restart.