One of the things that really bothered me about the GDM was no Compiz-Fusion Shadow around the login window. Compiz is obviously not present for good reason but it is possible to enable Compiz-Fusion on GDM if you can run Compiz. About 2 weeks ago I finally decided to mess with this a bit and found a way to do so that is quick and easy.

Since GDM does have a location available and supports .desktop files to applications that load on start, this is a pretty quick hack and can also be disabled easily.

In your terminal window, type the following.

$ cd /usr/share/gdm/autostart/
$ sudo vim compiz.sh

Now enter the following in our new file:

#!/bin/bash
compiz --replace &disown

Save the file and make it executable:

$ sudo chmod +x compiz.sh

Now, we need to create the desktop file:

$ cd LoginWindow/
$ sudo vim compiz.desktop

Enter following in the .desktop file:

[Desktop Entry]
Type=Application
Name=Compiz
Exec=/usr/share/gdm/autostart/compiz.sh

Save the file, logout, and you should have a shadow around the login window and the other default compiz effects will be enabled as well.