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.
If this is added, make sure to also add a 'Clean search history' button, or even a setting to auto-clean it on exiting the program.
A true search history would be a tree of sessions, each search, if any files where downloaded from that search, and the time of each action (or range, for session).
And by session I mean online time, or program open.
This feature would be SO useful!