gtk+: gtk+ (graphical user interface toolkit) gtk+: gtk+: GTK+, which stands for the Gimp ToolKit, is a library for creating gtk+: graphical user interfaces for the X Window System. This library is gtk+: needed for GIMP (the GNU Image Manipulation Program), Mozilla, and gtk+: many other X programs, including most of the programs from the GNOME gtk+: project. gtk+: gtk+: gtk+: gtk+: