Otk is a portable widget library for making graphical user interfaces for
application programs. It emphasizes simplicity without eliminating capability.
It is based on OpenGL and C. Otk provides the following basic widgets:
* Panel -		The "container" widget,
* Text Label -		Text labels,
* Button -		Buttons with labels and call-backs
		  	to user functions,
* Text Form Box -	Accept text with function call-back,
			also scrollable editor window,
* Pull-down Menu -	Display hierarchical menu-lists with user
			function call-backs on mouse release,
* Slider Control -	Slider control with call-back,
* Sub-windows -		Detachable self-managed windows,
* Gadgets -		High level widgets

WWW: http://otk.sourceforge.net/