From the official GTK+ web site [L1 ]:

"GTK+ is a multi-platform toolkit for creating graphical user interfaces. Offering a complete set of widgets, GTK+ is suitable for projects ranging from small one-off projects to complete application suites."

GTK stands for "GIMP ToolKit" and is licensed under the GNU LGPL.

The following projects use or interface with GTK+ in some manner:

 Description: Application framework built around a XML parser/renderer
        which supports GTK GUI apps in XML.
        Currently supports Perl, Tcl, and C for doing runtime XML creation
        and modification.
        Currently at version 0.7.2 .
 Updated: 06/2000
 Contact: mailto:[email protected]
        putting "subscribe entity" in the body of the message.
 Description: Tries to apply your gtk theme colors to Xt/Motif/Tk applications
        by setting variables based on the current them and piping them along
        with some other default files into an xrdb -merge command.
        Currently at version 0.2.4.
 Updated: 02/2000
 Contact: mailto:[email protected]
 Description: MMuCl (pronounced muckle) is a MUD (multi-user dungeon) client
        written in Tk 8.  MMuCl has been verified to work under Linux,
        Windows 95 and Windows NT.  Distributed under GNU Public License.
        Requires Tcl_Gtk .
        Currently at version 1.5.0 .
 Updated: 03/2002
 Contact: mailto:[email protected] (Mark Patton)
 Description: XML based application builder and thin client.
        Includes script engines and an API.
        Environment is GTk+/GNOME/Tcl/Perl.
        Currently at version 1.3.
 Updated: 07/2001
 Contact: mailto:bill at albacoretech dot com
 Description: Tcl/Tk oriented Ada-95 GUI builder, portable to different
        platforms such as Windows, unix, MacOS, and OS/2 .  You can use
        it as an IDE for any Ada-95 (C, C++, Tcl) project.
        Uses GNAT, TASH, RAPID, Tcl/Tk 8.x, Img, icons, Help System,
         TkPaint, BWidgets, mcListBox, mComboBox, Tktable, ftp_library, csh,
         snack, BLT, itcl, Tix, QuickTimeTcl, XanimTcl, Tcl-gtk, Oratcl,
         XBit, Tkogl, tom, Vtktcl, Tkhtml, Fve, August, ASED, TclDOM, Tclxml
         Whiteboard, TkMC, tkxmlive, IDL_To_Ada.
        Currently at version 6.0 .
 Updated: 08/2002
 Contact: See web site
 Description: Web C++ is a command line utility that converts your
        source code into an HTML file, with syntax highlighting
        and stylesheets.  Webcpp currently supports
        Ada95, Assembler, Basic, C, C#, C++, Cg, CLIPS, FORTRAN, Haskell,
        Java, Markup, Modula2, Objective C, Pascal , Perl, PHP
        Python, SQL, shell, Tcl highlighting.
        Webcpp gtkgui is at version 0.3.1 and is a GTK+ GUI for webcpp.
        Currently at version 0.7.5 .
 Updated: 07/2002
 Contact: See web site
 Description: Tcl binding for GTk+/Gnome.
        Version 0.0.1 is for Tcl 8.2 and supports only some GTk+ bindings.
 Updated: 09/2000
 Contact: mailto:[email protected]
 Description: PGPLOT display driver using Tk as well as ptcl's PGPLOT
        Tcl bindings.  Pgperl is a Perl 5 module to call pgplot.
 Updated: 08/1997
 Contact: mailto:[email protected] (Brian H. Toby)
 Description: A number of GTk widgets have been bound to Tcl 8.2,
        based on GTk 1.2.  Mmucl is an application that uses this extension.
        Currently at version 0.07 .
 Updated: 08/2002
 Contact: mailto:[email protected] (Mark S. Patton)
 Description: The wx is a new GUI extension to Tcl, based on wxWindows and
        wxGTK.  Its intention is to provide a developer with an extension
        able to provide a native look and feel, contemporary looking
        programming constructs, AND still be able to operate within a normal
        Tcl and Tk application!
        The developer has discontinued development of it, but the source
        is available from mailto:[email protected]
        if someone would like to continue work on it.
 Updated: 09/2000
 Contact: mailto:[email protected] (Olivier Paquay)
 Description: Perl Object Environment (POE) is a cooperative task scheduler.
        It includes interfaces to Tk, Gtk, and other event loops.  It provides
        lots of support for all sorts of protocols and functionality.
        Currently at version 0.22 .
 Updated: 09/2001
 Contact: See the web site
 Description: The GTK-server offers a stream-oriented interface to the GTK libraries,
        enabling access to graphical user interfaces for shellscripts, interpreted programming
        languages and of course TCL using either GTK 1.x or 2.x. The gui-server works on Linux
        and Windows with following interfaces: Linux STDIN, Linux TCP, Linux FIFO, Linux UDP, 
        Win32 STDIN, Win32 TCP, Win32 FIFO, Win32 UDP. The project is in active development.
 Updated: 11/2009
 Contact: See the web site

(DKF, escargo, and davidw were the original contributors of this page.)