Drawing widgets on existing sdl_opengl context

Is there any actively developed open-source (GPL is fine) library that can draw widgets such as buttons, menus, etc on an existing SDL/OpenGL context? I have heard of FLTK, but it appears that it creates its own window and its own OpenGL context to 开发者_开发百科draw widgets on.

Yes. CeGUI is perfectly capable of drawing into an OpenGL context (it doesn't care how you initialize OpenGL).