GTK+ 2.12.0 is now available for download at:
ftp://ftp.gtk.org/pub/gtk/2.12/
http://ftp.gnome.org/pub/gnome/sources/gtk+/2.12/

new features:

  • Tool tips can be placed on Widget and tree view
  • You can build your interface via changing XML discreption.
  • New widget and object,such as GtkVolumeButton,GtkScaleButton,GtkRecentAction and so on.
  • newFile Selector,surpporting search,display recent files.
  • improved test view and item widget
  • improved gdk-pixbuf

Pls see more from here:http://www.gtk.org/gtk-2.12-notes.html