@Renzo Bagnati: I think your problem is a different one.
Your AD users don't exist in /etc/passwd and unfortunately, the system-tools-backend only know how to retrieve information from /etc/passwd, so your AD users are considered invalid.
When the "Users and Tools" configuration panel retrieve the members of a group, it only gets the valid ones.
When you modify the group configuration, the whole /etc/group file is rewritten without the "invalid" ones as "Users and Tools" doesn't even know about them.
The same bug should happens with a NIS setup I think.
I think the good solution is to have system-tools-backend use the getent command rather than parse the /etc/passwd file.
But maybe you should file a separate bug for this.
@Renzo Bagnati: I think your problem is a different one.
Your AD users don't exist in /etc/passwd and unfortunately, the system- tools-backend only know how to retrieve information from /etc/passwd, so your AD users are considered invalid.
When the "Users and Tools" configuration panel retrieve the members of a group, it only gets the valid ones.
When you modify the group configuration, the whole /etc/group file is rewritten without the "invalid" ones as "Users and Tools" doesn't even know about them.
The same bug should happens with a NIS setup I think.
I think the good solution is to have system- tools-backend use the getent command rather than parse the /etc/passwd file.
But maybe you should file a separate bug for this.