Jay pointed me at this, and yeah this looks like a common -ati rendering issue, and is almost certainly a driver bug.
It is interesting that #685132 shows a similar error on -intel, but I've a feeling these two bugs are distinct (much of the rendering code is driver-specific). Even if they ultimately do share the same root cause, we may find it beneficial to treat them as independent driver bugs, until it is clearer where the fault is, just in case. Can someone who reproduces this bug please run 'apport-collect 684992' to give us a set of X log files we can forward upstream? ** Changed in: xserver-xorg-video-ati (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/684992 Title: Artefact in launcher tooltip and icons -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs