My goal is to get Limewire(JAVA) and Songbird(XULRunner) to run together.
I was thinking the best way is to run the XUL application(songbird) inside
I would examine Limewire's source code. If there's a clean separation between UI and the rest of the application, I would try finding a solution to instantiate and invoke Limewire's non-UI code from within a Songbird extension.