This issue relates directly to Gnome. I am intrested in changing the default color that is displayed behind the splash screen immediately following the graphical login. After some extensive reading in the Gnome admin-guide. I thought it might be a setting in a gconf.xml... either a mandatory, or default setting but after checking them I discovered the problem did not lie therein. The text explicity states that a gnome session begins immediately following a graphical login and continues until a logout. Because the time frame for the splash screen follows the graphical login I though that maybe there was a default gnome-session somewhere that was being used just before my user gnome-session was being used. Alas, I have been unsuccessful in traking down the problem. Any tips or a point in the correct direction would be much appreciated.

"A gnome session immediately follows a graphical login"

Strictly speaking that is not correct.

It all depends on how your GDM is configured.

Go to

/etc/X11/gdm/Sessions

and you will see a number of files with names whose appear
on the GDM session choice list on the GDM login screen.

As all of my files in there are completely customized and just point to running a singe file /etc/X11/Xsession which then calls lots of other files and eventually a /usr/local/X11R6/XSession file in which the window manager is eventually run, I cannot be specific about your files.

So you can in fact do all sorts of things before your gnome session
starts.

But if you edit the file named Gnome or gnome-session, you should be able to add a line to the top of the file (but after the first line
with #! /bin/sh)

xsetroot -solid orange

or for a nicer effect

xsetroot -bg "#334444" -fg "#889999" -mod 2 2

replacing "#334444" and "#889999" with the colors you want for a slight effect.

If you are not sure about color name to "#rrggbb" (r= red, g=green, b = blue, value is from 0 to f) format conversion,
install the program xcolorsel and run it.

And if you are interested, you can in fact setup a method to
change the splash screen to a random one from a collection
of them in a directory!

But this has to be done by root in the /etc/X11/gdm/PreSession/Xstartup file.

The same thing can also be achieved for a random GDM graphical login theme, if you are using GDM2 in theme mode.

Thanks for the tip! The xsetroot command was the key to my solution. On my system however, making a change in the /etc/X11/gdm/Sessions/GNOME did not refelect a change. So after a bit of searching I edited my /etc/X11/xdm/Xset_0 with a simple...

/usr/X11R6/bin/xsetroot -solid black

then I logged off and during the log off I noticed the color displayed was black, not the default bluegrey I had been seeing. So after a moment of jubulation I logged back in and to my dismay the dreadful bluegrey appeared under my splash screen! Yikes! I immediately checked my Xsetup_0 to see if a script had overwritten my manual edit, but that was not the case. After some additional reading and searching I discovered /etc/X11/xdm/Xsession I then updated it with

xsetroot -solid black

and once again logged out. Once again I logged in but this time the splash screen was black! Success!

Apparently a lot goes on during that half a flicker during splash screen. I'm not sure but it appears that xdm is running instead of gdm... or are both running? Anyhow thanks for the help.

"Apparently a lot goes on during that half a flicker during splash screen."

EXACTLY!

As I indicated above, you can in fact customize entirely the startup process and do lots of things in between the login and the actually starting of the shell script gdm-session.

In fact what you should do, is make sure that you have setup and configured SSH on your system, then run your Xsession as a sub process
of

/usr/bin/ssh-agent path_to_your_xsession_file

and in your xsession_file, run ssh-ask to enter your ssh password
so that you never need to provide a password during the session
to login to other hosts that you have also set up with your SSH public key.

To clear up any confusion, you will only have one display manager running for each display you have. Normally you just have one display :0 running on vt7, you could in fact fire up a second display :1 on vt8 if you insisted.

So you are either using xdm or gdm (or even kdm or wdm).

You should easily recognize which one by the type of widgets
used on the graphical login screen -- if they are of the gtk type,
then it is gdm.

Why not do a

ps -adef | egrep dm

so see whether there is a gdm or xdm process running?

And note that I did not say to edit the Xsetup_0 file to change the background color since this is run as root before the Display Manager greeter appears on the graphical login screen.

Okay, so here is a run down on the sequence

1) Xsetup -- things in this file are run as root before the Greeter appears

2) the user "logs in" at the Greeter, actually just authenticates

2) Xstartup is now run as root

3) Control is passed over to the user and for GDM
the session file matching the chosen session is executed
in /etc/X11/gdm/Sessions (which may in turn call /etc/X11/Xsession)
or for XDM the /etc/X11/Xsession file is called directly
Various things are set up in /etc/X11/Xsession and it looks for
the presence of various files in the user's home directory,
and eventually the desktop environment or window manager is started.

I hope this is a clear enough explanation