Created attachment 97449 [details]
Screenshot

I made the switch to XFCE desktop... at least for awhile.  Now I'm back to KDE
for the moment, but the artifacts occurred during xfce usage.  

Note: I stay logged in for weeks at a time.  I don't reboot - or logout, unless
something forces me to do so like a system update that requires a reboot... or
artifacts that obscure the window so I can no longer see what I'm doing; or
some other severe problem.