We're also interested in using background pictures in themes. Unfortunately, it isn't easy to do. If you'd like to modify the code, you're correct that it's all in Java. Pretty much every GUI component would need to be modified to handle this kind of change.
A change of this magnitude probably won't see the light until after LimeWire 5.0, which is some ways away. So that we have an idea of what to shoot for, though, how would you envision the background image to work? Would it be a single image for the entire application, or a different one for each tab, or ? |