Comment # 13 on bug 89980 from falaca@gmail.com

Good news! I saw this today:
http://lists.x.org/archives/xorg-driver-ati/2015-April/027345.html

So I built and installed Michel's xf86-video-ati repo and enabled TearFree in
xorg.conf. The corruption is now gone - so I suppose it was simply some
manifestation of tearing, but only after a suspend/resume cycle.

To test it, I installed the module, enabled TearFree, then did a suspend/resume
cycle, and I couldn't observe any tearing in the global menus. So then I
commented out the TearFree option in xorg.conf and restarted lightdm, and
immediately started seeing the really obvious tearing in the menus like in the
video I posted. As a final check, I uncommented the TearFree option and
restarted lightdm again, and the tearing was gone.

Thanks Michel! And I hope the TearFree feature will eventually be extended to
support rotated displays as well!