Hallo,

at the moment, I am using LXDE as desktop environment.

But I wanted to have a look at some different file managers recently, so I gave thunar a try. The problem is, I ran into authentication problems afterwards, and I suspected thunar to be responsible for it.

But the problems still exist after removing the thunar-related packages (via aptitude).

Now I neither can log in on the desktop as root in a terminal (convenient for copy&paste), nor is my user password accepted in xscreensaver.

I remember having a similar problem when I used gnome as DE and I think I have read something of the xfce-Packages being related to the gnome "basics", but I am not sure of that.

Does anyone have a suggestion how to solve that problem?

pcmanfm and thunar do not conflict in any way and the removal of thunar-related packages is not related to your authentication problems.

I would have a look at your logs (I don't use debian, but there should be some sort of dpkg log files.) to find out if you have uninstalled any packages that you had before you installed thunar.

Hallo, now I've examined my logfile:

The only other things I've installed at the same time were gamin instead of fam, kacpimon and grub (switching back to legacy, mainly because I couldn't figure out how to edit the menu in grub2) and a few updates from other programs. Maybe I have even used a version of grub that I had stored on another partition.

But as the problem did only occur on the GUI, and I didn't had any problems
logging in on a terminal, my first thought was that some desktop application would be responsible.

Deinstallation of gamin didn't help.

Could kacpimon or grub affect the authentication on the desktop?

Edit:

It was an issue of permissions. It only seems to work if the setgid bit is set for the su command