I have a Radeon R9 270 graphics card with openSUSE 42.2 and GNOME 3.20.2. I'm using the default open source driver. The AMD proprietary driver doesn't support 42.2. It's better than it was in 13.2, but I'm getting is a frequent horizontal flicker. Usually a few minutes apart. Is there a tweak for GNOME that might settle this?