The drivers probably aren't handling sync-to-vblank properly, so Clutter is timing out there. You can work around that by setting the environment variable
CLUTTER_VBLANK=none -- Earthling Michel Dänzer | http://www.vmware.com Libre software enthusiast | Debian, X and DRI developer -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]

