I set the station type to Stationless, tried it with firefox and still not working. If we are indeed running the same versions of the software involved, and it appears we are, the only other variable would be hardware so this may be a video driver issue - but that wouldnt explain why other apps work like the gtk3-demo. It appears you may be running a virtual instance of Ubuntu? Maybe that has some influence on this. Im gonna give up for now. Maybe I’ll try virtualizing it in the next few weeks.