--- Comment #7 from Andrei Borzenkov email@example.com --- (In reply to Fabian Vogt from comment #5)
Sounds like the display manager (or maybe X itself) selects the wrong VT.
1. If I disable auto-login I get lightdm greeter, I enter my user name and password and then I get blank screen (while session is completely launched).
2. I installed GNOME/X11 and if I select gnome X11 session in lightdm, I get normal fully functional GNOME desktop.
3. I still get blank screen if I log out of GNOME and log in into Xfce again.
So it is really Xfce issue and it looks like some OpenGL/HW acceleration/whatever is missing in Xfce. But I am not familiar with it deep enough to even start digging. If anyone has any idea where to look ...