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:
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.