I can confirm this behavior. According to the /var/log/auth.log, gksu is attempting to open /usr/bin /software-properties, which does not exist. Instead it should be targeting /usr/bin/software-properties-gtk.
Synaptic does not have this problem, it appears to only affect the gnome-control-centre. -- cannot acces to the "select pkg sources window" https://launchpad.net/bugs/84465 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
