If I switch user in a terminal. su bob I can't open gedit because bob doesn't own the display. If I execute xhost + before switching to bob I can open the display for some applications but not all. I get the following output when trying to execute gedit: (crashreporter:4415): GnomeUI-WARNING *: While connecting to session manager: None of the authentication protocols specified are supported. * GLib-GIO:ERROR:/build/buildd/glib2.0-2.28.6/./gio/gdbusconnection.c:2279:initable_init: assertion failed: (connection-initialization_error == NULL)