I have both Unity and GNOME desktop environments installed in 17.04.
When I'm in the Unity environment, I occasionally get video glitching on my laptop's internal screen. Large flashing black blocks that cover most of the screen. Showing all workspaces stops the video glitching.
When I'm in the GNOME environment, I don't see that same video glitching (yet) that I see in the Unity environment.
I believe that both use lightDM as the display manager.
Compiz is used in the Unity environment, but not in GNOME. I tried setting compiz to use "low quality graphics" mode, hoping that it might disable some/all of the compiz eye candy, and that doing so would give me a clue if compiz was to blame. But it still glitches.
I have one more clue that may, or may not, be related. When I wake the display from being dimmed and locked, the login screen blinks... that is... it shows the login screen, blinks, and then shows the login screen again.
I haven't given you to much to go on, but does anybody have any idea as to what might be going wrong? Otherwise my system runs solid.
In 17.04, what's the correct way to reset compiz, unity, lightdm?
Update #1:
output of lspci -k | grep -iEA3 '3D|VGA'
00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 09)
DeviceName: Onboard IGD
Subsystem: Toshiba America Info Systems Haswell-ULT Integrated Graphics Controller
Kernel driver in use: i915
lspci -k | grep -iEA3 '3D|VGA'– Byte Commander May 27 '17 at 21:42