I've written a modest menu bar/document framework for GLOW/GLUT/OpenGL. This allows writing applications with menu bars and menus on top of GLOW, and manages most of the details of doing so. Here's a preliminary document.
The general idea is to provide a way to write modest OpenGL applications without having to deal with the 2D GUI system at all.
GLOWaux is based on GLOW, which uses GLUT, so it's usable on any platform that supports GLUT.
Is this useful to others?