I used the inofficial guide of this forum for upgrading. After upgrading I´m asking myself how to check if the new GUI (GTK v3.0?) is already in use.
I have e.g. Synaptics Package Manager which is almost completely black when running. It worked (nice new GUI) for some time meanwhile, but after a few reboots -> back to "defect GUI"
You can see the gui issue on this screenshot: [attachment]screenshot.png[/attachment]