Hey,
just to lt you know I just updated the GTK API docs on http://www.geany.org/manual/gtk/. There are now the latest available versions(*) of GLib, GObject, GDK, GDK-Pixbuf and GTK online and a tarball containing all docs: http://www.geany.org/manual/gtk/gtk-doc-2.8.tar.gz
(*) latest versions of the 2.8 series available on http://library.gnome.org/.
Regards, Enrico