... and all APIs making use of it.
That code like it hasn't been touched in years, Google codesearch
didn't find any users and most importantly it's a horrendous API, so
let's just make it die instead of having to port it over to
non-GdkNativeWindow usage, which would be required for multi-backend
GDK.
http://mail.gnome.org/archives/gtk-devel-list/2011-January/msg00049.html