Here's a brief writeup of a simple (9 KLOC, 340 KB binary) but capable and portable OpenGL GUI:
Obligatory screenshot: ui.png 42.07KB 3 downloads
Header files are attached: ui_headers.zip 5.62KB 47 downloads
I'd love to get a discussion going on any perceived shortcomings of this approach, missing features,
alternative libraries that didn't show up in my search, and your thoughts in general.