XFCE 4.8.0 logs out instead of shutting down

[michal.s at free-media.eu]

> I'm not sure this is related directly, but in Debian testing GDM became 
> obsolete. Nowadays new installations of Debian testing with Xfce use 
> XDM.

I don't think this is related with this problem. I use Xubuntu, where GDM
is used, and the problem is showing up sometimes. But it may be caused by
some kind of dropping GDM privilages. I don't know... Next time I will look
into the logs.