Very cool! A few things for you to consider: 1. Consider putting preferences in their own window. This is the standard Mac behavior, and it's a little confusing to have your app do something different. You could also use the standard preferences toolbar look. 2. The artwork for your playback controls looks off. Specifically, I think the anti-aliasing of the circles looks uneven. 3. For the gear menu at the bottom lef…
6. I was very surprised that spacebar didn't control play/pause and was even more surprised that there is no keyboard shortcut for play/pause.
Seems to work for me.