I just completed a Tumbleweed distribution upgrade.
With OpenGL enabled the screen flickers wildly making it unusable. I have now switched to XRender for the time being and everything is stable.
Where do I begin to sort out my OpenGL installation?
Operating System: openSUSE Tumbleweed 20181224
KDE Plasma Version: 5.14.4
Qt Version: 5.12.0
KDE Frameworks Version: 5.53.0
Kernel Version: 4.19.11-1-default
OS Type: 64-bit
Many people have experienced this issue.
Removing packages xf86-video-intel or xf86-video-nouveau or both should fix it for you.
https://forums.opensuse.org/showthread.php/534273-Upgrade-to-20181218-killed-all-but-one-graphical-login?p=2889655#post2889655