I think it would be nice to be able to rightclick the icon in the tray, and change play order from there. For instance, if I hear a nice song in my playlist, I might feel like putting it on repeat, or I might want to shuffle that album.
It would be nice to change the playmode without having to open up the big interface to do it. Is this currently possible, with or without a plugin? If not, is there anyone that would like to program it?