> It's not a screenshot of someone logged in that I need.
> It's a screenshot of the gdm login screen, where you
> select your session type and language (if you want),
> and type in your login name and password.

> And this is as it ought to be. Am I missing some subtle
> thing I never knew about in your suggestion? 

Yes, I did misunderstand, now the question is do I continue to help give 
you the right answer or walk away and let you sink because your response 
was so condescending? (I will go on the presumption you are just 
frustrated and possibly even trying to be funny)

In gdm.conf, in the [Greeter] section there is a value BackgroundProgram=, 
you can put in a program to do screenshots or a script here.  Say 
/usr/bin/X11/gimp or such.  You can edit the file manually or do so via a 
GUI if you have configured to do so.

I created some samples:
http://gnuenterprise.org/~dneighbo/screenshots/login.png
http://gnuenterprise.org/~dneighbo/screenshots/configuration.png

If I have again misunderstood I apologize.

-Derek