Close button sends client to the tray, statically linked Qt for OSX.
See the Changelog for list of features and fixes currently only available in the nightly builds.
There's an existing suggestion for clearing finished downloads, I'm renaming this one to 'Show different colors for different transfer statuses'.
This is mainly already done, but sometimes the color isn't always correct for the status. e.g., when a user goes from queued to complete, the status word changes, but the color remains blue until you expand the user. I think it then changes green, but maybe you have to collapse it again. I forget the exact procedure that I used to get the color updated.
You're right, I'll fix it soon.