Looks lilke a rendering artifact due to the ATI driver. The ALT+tab crashing the window manager is also tracked as #691653
** Tags added: driver unity ** Also affects: xorg (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg in ubuntu. https://bugs.launchpad.net/bugs/687445 Title: The strange white lines appeared on the top of screen _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp