Comment 7 for bug 1503159

> Does this bug render the system temporally unusable?

see https://launchpadlibrarian.net/221306726/20151015_065628.jpg from https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1506384 for after click on button in Thunderbird and before login is possible. It happens happens too sometimes in LibreOffice and Firefox.