It would be good to have toolbar/deskband mode, so that user can see what is currently playing and use simple controls without requirements to switch to main window. Something like this:

Or maybe some kind of API (not deezer API, but instead desktop app API), so that third party developer can send commands to desktop app and receive information about current playing track, that way it would be simple to implement toolbar controls.

This will greatly improve desktop app usability when listening to music, wile doing some other work.