Just as GTK+ is build on top of GDK, GtkGLArea is built on top of
gdkgl which is basically wrapper around GLX functions. The widget
itself is very similar to GtkDrawinigArea widget and adds only few
extra functions.

Lower level gdkgl functions make it easy to render on any widget
that has OpenGL capable visual, rendering to off-screen pixmaps is
also supported.

Homepage:
http://web.archive.org/web/20011204180640/http://www.student.oulu.fi/~jlof/gtkglarea/
