The Fast Light Toolkit is a cross-platform Graphical User Interface (GUI) library written in C++ and can be use on UNIX/Linux, Microsoft Windows(tm), MacOS X(tm), and many other operative systems, it support 3D graphics via OpenGL and built-in GLUT emulation, small and modular enough to be statically linked, and also as a shared library, includes a What You See Is What You Get (WYSIWYG) user interface builder called Fluid.[LGPL]