I\'m confused by the GTK terminology. According to Wikipedia, there seem to be bindings to GTK+ that are called GTK (GtkAda) and GTK2 (gtk2hs, Gtk2-Perl).
GTK/GTK+ and GTK2 are different versions of the same API. GTK is an old, deprecated version, GTK2 is the previous one, GTK+ 3/GTK3 is the current version.
GTK+ is the correct name of the old API, but most people just call it GTK.
The C++ bindings for GTK+ are part of the project GTKmm.