TODO.txt

-> When something goes wrong with a file, make sure "on player", "coming" and
   "leaving" lists stay in sync.
-> Display dialog on start-up if no player selected, encouraging user to do so
   now.
-> Independently track what user checked and what is on the device.
-> Enable/disable "eject" and "sync" buttons correctly depending on whether
   there still is a player or not.
-> Make icon/disclosure triangle column automatically become larger if indent goes deeper. Otherwise icon draws half across name.
 √ Allow syncing whole playlists. If tracks are removed from such a playlist,
   they should automatically be deleted from the player next time we sync, and
   if ones are added they should be copied over. Option-click checkbox to just
   select all tracks that are *currently* in the playlist?
 √ We're probably confusing users with a brushed-metal-behaving Aqua window.
   Find a better pattern.