I did a quick mockup to illustrate what i mean
http://i.imgur.com/36MJg.png1. Give the search and address field a 1px rectangular border.
2. Get rid of the icon for 'now playing' list. It's unnecessary and when you open 'now playing' in the main panel the icon in the right panel stays even though there's no 'now playing' list anymore. as ma_t14 pointed out it serves a function
3. Make the headers of track browser (and now playing list) look like the headers below it.
4. If there is nothing to scroll hide the scrollbars.
5. Make the selection in navigator panel full-width.
6. Replace those expand buttons with arrows.
7. Get rid of the now playing/selected bar. Instead change it through right-click menu (same in lyrics panel).
8. Display a notification with remaining time if user activates the auto-shutdown. (also can you add a option to shutdown when a current song finishes, this would be very handy for lengthy podcasts)
Good ideas? Bad ideas?