This has been a collection of files required to build Quodlibet.app:
Quodlibet as a native GTK+ Quartz application for Mac OS 10.6 and later.
QuodLibet.app is now part of the main developement.
Get it from http://quodlibet.readthedocs.org/en/latest/downloads.html#macosx
Go to https://github.com/quodlibet/quodlibet/tree/master/osx_bundle to see how it's done.