Go to yast --> network services --> remote administration (vnc) and enable
'Allow Remote Administration' and then then reboot your machine.

Open Firefox, go to localhost:5801
A Java application will start loading and then you will see gdm within firefox.
Login with your credentials and Gnome session will start.

Then try to log out... You can't. (bug)

Normally it should let you log out. If not bring you to the gdm screen, it
should  at least terminate the vnc connection. However, none of the happens and
you still connected and working remotely as if you never clicked the 'logout'
button.