In the manager window/tab whatever it's called if you right click a file in the file tree you can "Build file". As I'm remembering it this is supposed to build only that file, right? i never use it, but thats how I'm remembering it was made for. Anyways I does not work in osx snow leopard. Only thing that appears to be happening is the following output in the Build Log: make: *** empty string invalid as file name. Stop.
I don't have access to a windows/linux machine at my office at the moment so I cant say if it woks under those systems.
C::B rev. 7456 built in late September so I guess this might be kind of old news.