Question 2: Extendible OpenGL GUI library

[janderson]

Thanks for all your answers on my previous network library question.

The second thing I'm looking for is an extensible, portable GUI library. 
  Eventually I want and need the ability to improve and add my own types.

The most important control I need is a multi-line textbox which I can 
add functionality to as I need it.

I was thinking that openGL would be cool (although not necessary) as I'd 
be able to do some neat iphone like stuff (and 3D GUI's) one day in the 
future.  So it would be nice if these gui's were made out of 3D polygons 
or renderable on a texture.

So far luigi looks like my best option: 
http://www.dsource.org/projects/luigi

I want to avoid writing my own GUI library because I know I do I'll 
never get this project done.  I'd rather not port something, although I 
will do if its worth it.

What do you use?
What libraries do you suggest and why?

-Joel

PS - Does anyone know if its possible to render controls like scintilla 
on to a openGL texture?