up2date/seaudit/... not working (EXPLAINED)

[Tom London <selinux@xxxxxxxxxxx>]

Running off of the development tree, I couldn't get graphical apps (like 
up2date, seaudit, ...) working when su'ed as root.  All of this works 
fine on a 'stock FC2' machine (running off
of the base and released-updates trees).

The problem seems to be that the latest packages cause 'su' to change 
the settings of XAUTHORITY environment variable from 
'XAUTHORITY=/home/USER/.Xauthority' to
'XAUTHORITY=/root/.xauthABCD'  (ABCD the usual 'uniqueness' stuff).

If you manually reset XAUTHORITY back to '/home/USER/.Xauthority', the 
apps work
again.

Here's a bit of added strangeness: if you start 'xauth' in another user 
window and then
try 'su -l', XAUTHORITY is not changed in the root shell.  No AVCs against
/root/.authABCD either....

[On the 'stock FC2' machine, XAUTHORITY is not modified by su.]

I've bugzilla'ed this 
(https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=126300)
against coreutils, but I'm not sure that is the right place (e.g., 
pam?). (All my systems
run with SELinux enabled, so I can only assume this is occurring on 
SELinux-disabled
systems as well.)

Can someone explain why 'su' would be changing XAUTHORITY ?

thanks,
  tom