[cairo] How to use Cairo glitz backend in existing FLTK OpenGL window?

[ml.user at op.pl]

Hello,

My name is Robert, I've used Cairo for few months. I write some
components for complex system and I try to use Cairo as can as possible (mostly Cairo is used as SVG renderer). Since now ussage
cairo_image_surfrace was been enough, but now I think that maybe using glitz increase performance.  

I want to use glitz backend for Cairo. I really care about that glitz
renders to existing OpenGL window, offered by FLTK library. I'm going to use Cairo 1.0.2 with glitz 0.4.4 and FLTK 1.1.4. The operating system is Linux Debian Woody and Sarge.

I asked for help, because I haven't used glitz, I didn't find any
tutorial neither documentation for glitz. I noticed in examples
(cairogears, http://www.cherustone.com/cairo.cpp) that glitz create own OpenGL window.

I don't want that glitz create own OpenGL window, rather I prefer that
glitz renders in Fl_Gl_Window created earlier by application.
Fl_Gl_Window is the OpenGL window provided by FLTK library. I want to be able to mix Cairo + glitz rendering code with other OpenGL rendering code which nothing know about Cairo and glitz. 

Thanks for help in advance.
-- 
Robert
ml.user at op.pl