To build this Gtk# from trunk is required and the following patches:

http://bugzilla.novell.com/show_bug.cgi?id=323372
http://bugzilla.novell.com/show_bug.cgi?id=501685

If you're using Mono < 2.4 you also need to apply:
http://bugzilla.novell.com/show_bug.cgi?id=477396