Great!
Where does openSUSE stow the configuration files for display managers, e.g. XDM and LightDM?
Each has its own location(s) usually in /etc/. KDM3 is an exception. LightDM is in /etc/lightdm/. man lightdm
$ locate XDM does not work (I saw it on the internet)
$ which XDM just points back to /usr/lib/X11/displaymanagers which is not much help.
Linux filesystems are case sensitive.
# locate xdm | wc -l
435
# which xdm
/usr/bin/xdm
# which lightdm
/usr/sbin/lightdm
# which kdm
/opt/kde3/bin/kdm
# ls -Gg /opt/kde3/share/config/kdm/kdmrc
-rw-r--r-- 1 22694 Jun 3 19:09 /opt/kde3/share/config/kdm/kdmrc