Mozilla Suite themes
From MozillaZine Knowledge Base
Resources to change the look and feel of the Mozilla Suite
Splash screens
You can change the default splashscreen in the Mozilla Suite by creating a .bmp-file and place it in the same diretcory as mozilla.ex (Windows)
There is an unoffcial installer for Mac (in the works not ready yet) [1]
If you want to change the splash screen on linux you gotta build rpm source and change splash.xpm
Themes:
Promotional buttons: