Probably a duplicate of #2732. There is a patch at https://bugs.freedesktop.org/show_bug.cgi?id=70675 referenced in https://github.com/ValveSoftware/steam-for-linux/issues/607#issuecomment-27542348.
Yes, very likely a video driver issue.
@Freddi this was fixed with xf86-video-ati 7.3.0.
Closing as this appears to have been fixed some time ago.
As seen on the screenshot. Using Ubuntu 13.10 Desktop 64-bit with the Gallium free software graphics processing unit driver.