Comment 1 for bug 750521

A couple of things: (this is as much for the general developer population as it is for the reporter)
We don't currently support having multiple library directories (i.e. multiple roots for the library). This is (I think) an easy fix/change.
More difficultly, Qt doesn't have any way of telling us that what was selected was actually a collection of directories, not a real directory. Originally, Qt just returned nothing (which is what you're seeing now, their 'fix' won't be released until qt 4.8 if I'm reading right), and their fix is to just disable the selection of Libraries, which isn't a fix at all. Unfortunately because Windows 7 Libraries are such a unique/peculiar feature I'm not sure this will be changing particularly soon. (other mixxx bug: https://bugs.launchpad.net/mixxx/+bug/695913 qt bug: http://bugreports.qt.nokia.com/browse/QTBUG-12655 qt fix: http://qt.gitorious.org/qt/qt/commit/a6006b9b97634ae93e2ccc2dd93c0161e69d55dc )

Anyway, times like this I'm tempted to write native code but that's a pretty gross solution. Hopefully, this is something that we can figure out one day, because we're stuck with this from MS at least until the next Windows, if not much longer. The feature really isn't a bad idea, shame they couldn't have just implemented it with NTFS symlinks or junctions or whatever they're called.

Thanks for the report Daniel!