OpenGL program under Cygiwn/XFree86

[Wang Yi]

I am trying to compile a simple glX/OpenGL program under Cygwin/XFree86. 
The building process is OK. But the glXChooseVisual always returns NULL 
at runtime.
This program has been compiled under many UNIX environments and runs 
properly.
I have changed the attributed array passed to glXChooseVisual many 
times, but it still does not work.
I use the header files at /usr/X11R6/include and libraries of 
/usr/X11R6/lib/libGL.a and libGLU.a.

Cygwin/XFree86 does support OpenGL, right?
Cound anyone send me a simple model OpenGL program which can be built 
and run under Cygwin/XFree86?

Thanks a lot.