Windows Toolkit <li> GTK : The GIMP Toolkit, or 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. </li><li> QT : Qt is a complete C++ application development framework. It includes a class library and tools for cross-platform development and internationalization. </li><li> WXWidget : wxWidgets is a mature open-source cross-platform C++ GUI framework for Windows, Unix, Linux, MacOS. It can make use of a variety of native widget sets as well as its own widget set: WIN32, GTK+, Motif, MacOS. wxWidgets will even run on embedded systems using Linux and X11. </li><li> TK : TK is an X11 toolkit implemented with the TCL scripting language. Click on the following for information about specific TCL commands </li><li> FLTK : FLTK (pronounced “fulltick”) is a cross-platform C++ GUI toolkit for UNIX/Linux (X11), Microsoft Windows, and MacOS X. FLTK provides modern GUI functionality without the bloat and supports 3D graphics via OpenGL? and its built-in GLUT emulation. It is currently maintained by a small group of developers across the world with a central repository on SourceForge. </li><li> FOX Toolkit : FOX is a C++ based Toolkit for developing Graphical User Interfaces easily and effectively. It offers a wide, and growing, collection of Controls, and provides state of the art facilities such as drag and drop, selection, as well as OpenGL widgets for 3D graphical manipulation. FOX also implements icons, images, and user-convenience features such as status line help, and tooltips. Tooltips may even be used for 3D objects! </li><li> XForms : XForms is a GUI toolkit based on Xlib for X Window Systems. It features a rich set of objects, such as buttons, scrollbars, and menus etc. integrated into an easy and efficient object/event callback execution model that allows fast and easy construction of X-applications. In addition, the library is extensible and new objects can easily be created and added to the library. </li><li> LessTif : LessTif is the Hungry Programmers’ version of OSF/Motif?. It aims to be source compatible meaning that the same source code should compile with both and work exactly the same! LessTif is “free software”: it is licensed under the GNU Library General Public License (LGPL). You might also want to check out The Open Source Web for a little more information about the Open Source philosophy in general. </li>