I was able to reproduce this bug, that is make it gitk look like the broken.jpg screenshot, by:
1. Removing xserver-xorg-video-intel 2. Logging out and logging back in again. At that point, it looked like broken.jpg. Then I installed xserver-xorg-video-intel, logged out, logged back in again, and gitk was drawing happy little circles again. This is on Ubuntu 16.04. The xserver-xorg-video-intel driver is 2:2.99.917+git20160325-1ubuntu1.2. xserver-xorg-video-all is 1:7.7+13ubuntu3
