PyOpenGL

I've added an optional flag CHECK_CONTEXT, which will do explicit checks
for context before running any function.

Ah, sorry, missed the comment. Recent X11 mesas are *very* picky about GL
calls before context initialization, probably 3/4 of the OpenGL API will
cause seg-faults if called before context init. Guess I need to be helping
people with this somehow...

Don't see the bug on 64-bit Ubuntu Jaunty with bzr head
(Demo/NeHe/lesson18.py works), will have to get a 32-bit version to test
with.

Workaround found:

This failure does not occur if there is a currently active GL context with
a defined size. My app uses a class that creates a Quadric on class
initialization, which may occur before creating the GLCanvas the class will
eventually draw in. My test scripts don't use a drawing context at all -
just import GLU and call gluNewQuadric. If I postpone creation of the
Quadric until after the GLCanvas is created, sized, and SetCurrent, then
there is no problem. I am testing with the wxPython GLCanvas context. I
guess the same behavior would apply to OpenGLContext, but I haven't tested
that.

I still consider this a minor bug, or at least a documentation failure.
Creating a Quadric object (without using it to draw anything) shouldn't
really require an active drawing context. It doesn't on Windows, Mac, and
earlier versions of X11. If it is a new design decision to prevent this on
X11 it should A) be documented somewhere, and B) fail with a Python
exception, rather than a seg fault if possible. However, now that I know
about this, it is a pretty easy workaround to simply create the Quadric
only when it is needed to draw something immediately, so the segv doesn't
pose any serious problems for me anymore.