Using 64-bit 13.1 remotely, I ssh in and do:
jar@jarfx:~> su -
jarfx:~ # yast2 &
This works. Then (the next morning) I made some ssl certificates, and tried to edit the configuration:
jarfx:/etc/apache2 # nedit /etc/sysconfig/apache2 &
jarfx:/etc/apache2 # NEdit: Can’t open display
This happens all the time after a sufficient delay. Exiting su and redoing su - does not fix it. I have to log out and start a new session.
That is of course a pity because what you describe is technicaly a bit strange. But the lack of answers could be due to the fact that nobody else would leave open an inactive root session for such a long time. And I guess also nobody will try to recreate your problem by leaving an unattended root session open on his/her own systems out of security concerns.
Well, I am not worried about root access because my Mac is right next to my Linux server in my house. But it is not a root issue. If I exit root, I still cannot forward X11. Something changed, either in Mavericks or in 13.1 because now there is a default 20-minute X11 forwarding timeout. You need to add
to override this. A really long timeout crashes the Apple XQuartz server by the way.
I am testing that right now, in 13.1. I guess I have to wait 20 minutes to see.
The “ForwardX11Trusted yes” is all about that timeout, and has nothing to do with use by root. This change to “openssh” defaults happened several years ago. As far as I know, opensuse has always overridden this by putting “ForwardX11Trusted yes” in “ssh_config”. But, just in case something else has changed, I’m doing a 20 minute test.
Note that “ssh -Y” (instead of “ssh -X”) is also supposed to override this on a per-connection basis.