I recently upgraded from 13.2 to Leap 42.1 to Leap 42.2. Now I am getting the message in the title when running quite a few different programs. I've tried reinstalling all the oxygen theme stuff, uninstalling all the oxygen theme stuff, reinstalling the GTK stuff but still get that message, even when there's no trace of oxygen on my system.

I can only assume there's a cache somewhere that's not getting updated.

Any help appreciated!