gtk+: gtk+ (graphical user interface toolkit, version 1.x) gtk+: gtk+: GTK+, which stands for the Gimp ToolKit, is a library for creating gtk+: graphical user interfaces for the X Window System. gtk+: gtk+: This library has been largely replaced by GTK+ version 2, but there gtk+: are still some good programs that require it. gtk+: gtk+: gtk+: gtk+: