What is the license for the preinstalled themes on the n900. The gtkrc file is licensed as CC share alike 2.5, but is this license only covering the text-files or do they apply to the pixmaps as well?

I am mostly wondering since I am working on a theme, where I intend on keeping most of the elements intact, and mostly tweak colors and hues. I feel it is wise to ask now and not rush to do unnecessary pixelwork on every single element...

And a little bit OT ... Where is the color of the date in the lock screen defined?