F16: GDM user list, only show GDM logins

[Rich Boyce]

Hello list,

I'm rolling out F16 in a enterprise (well, academic) environment, and I 
need to get the GDM user list to only show users that have logged in via 
  GDM. At the moment it also shows users that have logged in via SSH.

I know that the new GDM uses systemd-logind to list its known users, but 
I haven't been able to find out how to configure either GDM or 
systemd-logind to list just GDM users (or just users assigned to a 
'seat', as SSH users apparently are not).

Is there a configuration option for this? I'm not keen to move to kdm.

Thanks a lot,
Rich