It's not a desktop widget, it has a flag set on it (see setAttribute()) so it's always on top, so either hide it when you're not on the desktop (I think there's a gconf key for that) or remove that flag (I doubt it'll stay on the homescreen though).

Oh and I fixed the call thing some time ago, I might push a new version soon I guess, https://gitorious.org/mediabar/media...91ae31f367bab7