The attached patch against Emacs 23.1.1 fixes this bug for me. The
patch can be used by emacs users and Linux distributors - who might
need to lower the required GTK version. However, the patch would
probably need to be modified before being checked in to emacs CVS,
because it specifies a dependency on a very recent version of GTK - a
more suitable patch for emacs CVS would use the C preprocessor to
perform the old behaviour for old GTK versions, and the new behaviour
for new GTK versions.