This guide will explain how you can change you're gdm gtk3 theme with fedora 15
prerequisite: gnome-tweak-tool and a terminal (gnome-terminal)
( insert password)
Now we are root and the first step is to install gnome-tweak-tool
if you already did this skip this.
yum install gnome-tweak-tool
Now we make the gdm user available to make changes:
# xhost +SI:localuser:gdm
If you did this right you get this message:
localuser:gdm being added to access control list
Next we will fire up gnome-tweak-tool
# sudo -u gdm gnome-tweak-tool
This will start gnome-tweak-tool as the user gdm (sudo -u username will start the application as designated user)
Now we can change the interface gtk+theme, icon theme and cursor theme to whatever you like.
Don't forget to change windows current theme to what you want.
How to change gdm login background:
# sudo -u gdm gnome-control-center
Here you can change the background
And when you're done exit the gnome-tweak-tool or gnome-control-center and type:
(ps the # sign is the sign you're running the command as ROOT don't copy it!!
This guide has been made thanks to www.archlinux.org
fine wiki about gdm.