● Originally written, along with Gimp, by Peter Mattis and Spencer Kimball in 1995 for a project at UC Berkeley in CA. As they wrote Gimp, Peter didn’t like motif, so he wrote Gtk to replace that.
● Later, Gtk was re-written to support some object-oriented features, and was then renamed to Gtk+. It later became adopted by the GNOME Foundation. Some began calling it "Gnome Toolkit". In Feb 2019, they dropped the "+". It’s just "Gtk" again.