One of my favorite things about Linux is the ability to customize everything. The Gnome Display Manager (GDM) is an excellent example. A quick look at gnome-look.org illustrates the diversity and choice Linux users have for a screen they might only see for 5 seconds.

Changing your GDM was once a simple processes with an excellent GUI behind it. With Ubuntu 9.10 Karmic Koala the GDM has been rewritten to properly take advantage of xsplash, Ubuntu's new X based boot. While these changes will significantly improve boot time, customizable GDMs are going to suffer. Ubuntu developers have already stated that a level of customization once offered with the old GDM will not be available for Karmic.

On the Left is the old GDM configuration screen. notice the options and themes you can choose from.

On the Right is the new GDM screen. Not many options.

I found two ways that we can hack the GDM to change the background, theme, fonts and some minor features. While not as robust as before, it's better then the ugly default brown.

Option1:

1.Click on Applications > Accessories > Terminal
2.Type:

3.Next logout. The "Appearances" window will open here, you can change the background & theme to whatever you like.
4.Once done, close the window and login, then remove the desktop file: Click on Applications > Accessories > Terminal
5.Type:

Option2:

1.Click on Applications > Accessories > Terminal
2.Type:

3.The "Appearances" window will open here, This will change the GDM background & theme to whatever you like.
4.Once done, close the window. The next time you login you will see the new background.