[GtkGLExt] begin opengl

[ivan danicic <ivand blueyonder co uk>]

Hello All, is it correct to do this:
define a C-function (at the top level) which may contain opengl items
without using "gdk_gl_drawable_gl_begin(...)" and the corresponding 
...gl_end(..) and using them only when the function is called?
Thanks in advance for your thoughts.
Ivan