These are the main files that I edited to alter my UI to the "blue" color, changing from the default "red":
- buttons_master.dds
- commonelements.dds
- specialelements.dds
- widgets03.dds
- window_elements_generic.dds
- window_elements_specific.dds
- windowelements.dds
So feel free to use those and alter them to your heart's desire and post a zip/image of your work. I'll gladly add alternative appearance zips to the updater, since they are completely optional.