Comment 1 for bug 145294

I assume that you are on a system, which is not equipped with an nvida-based graphics-card. But it would be helpful, if you could further describe your hardware-configuration. That's generally a good idea :)

What you describe sounds very likely to be the well-known shortcoming of the Xorg's DRI. GLX-client applications are always rendered into the front-buffer, ignoring the fact that they are running under a composited environment and thus should not do so. That very fact causes the glitches you are experiencing. Once DRI has "redirected direct rendering" this will automatically solve the issue you are encountering.