I just ran into two things sharing /usr/X11R6:

1. /usr/X11R6/lib/X11/xdm/authdir is expected to be writable *at least*
   by kdm, but I guess also by xdm. This can be changed in
   /usr/X11R6/lib/X11/xdm/xdm-config by setting:

	DisplayManager*authDir:                /var/run


2. /usr/X11R6/lib/X11/xkb/compiled needs to be writable. I have solved
   this with a symlink to /var. Now my german keymap works in X.


I thought that someone might be interrested in that. At least it's
documented in the archives now. :-)


 - Hubert

-- 
Hubert Feyrer <hubert.feyrer@informatik.fh-regensburg.de>