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.
You'll notice a small edit box at the bottom of every search results and browsed share window in the latest nightly build of SoulseekQT. As you type into it, any results or files and folders not containing the words being typed will be filtered out. Although I've already stumbled across many scenarios where this can be very useful, I realize it's not exactly the kind of filtering some of you have been asking for. One feature request called for file type and bitrate filtering. Well, file type filtering is already sort of possible. For example, add ".mp3" or ".ogg" to your filter, and only folders containing these file types will be shown. Bitrate filtering is not yet possible. But a general file attribute filtering scheme shouldn't be too hard to add to the existing mechanism. Imagine using such tokens as "attr:bitrate>=192" or "attr:vbr" in your filters. You get the idea. This is definitely something that can be done in the long run.