There have recently been some stories about applications switching away from GTK+ due to portability concerns. Therefore, I’m really happy to announce that we now have official GTK+ 3 builds for Windows. Currently, the supported version is 3.6.4. You can find these on the very informative download page:

http://www.gtk.org/download/win32.php

The driving force behind this was Manuel Bachmann (Tarnyko on irc). Thanks, Manuel !

We also have a page with instructions for GTK+ on OS X.