The intent is that you specify GLUT_OFFSCREEN as a GLUT display mode,
and then open a "window" much as you would a regular top-level window.
Only UNIX_X11 is supprted at this point, for lack of knowledge.
+
+*********************************
+* Ides of March, 2004.
+*********************************
+
+(184) Per demands of project owner, offscreen rendering is now removed
+from freeglut.