Found this Mir bug report - https://bugs.launchpad.net/mir/+bug/1144467 The fix is supposedly http://bazaar.launchpad.net/~mir-team/mir/xf86-video-ati-vladmir/revision/2538 I dont know if this has been upstreamed. Posting it here to see if Michel gets any clues seeing this. I don't see the original problem anymore, but I do get the same issue reported here - https://bugs.freedesktop.org/show_bug.cgi?id=90406 with the latest Arch linux build.