https://bugs.freedesktop.org/show_bug.cgi?id=100687
--- Comment #5 from MirceaKitsune sonichedgehog_hyperblast00@yahoo.com --- (In reply to Michel Dänzer from comment #4)
I temporarily set KWin back to egl and added the following to my ~./profile file:
export LIBGL_DRI3_DISABLE=1
This did not affect the problem: Window decorations are still completely invisible, when using egl over glx for rendering.