* It seems like on nv windows we need to explicitly rebind the main context to
the main thread and give each worker thread its own window, to prevent the
worker thread from being unable to bind its context sometimes.
* This is a very big blunt hammer for fixing the problem of multithreaded
submission from GL. Every GL call checks to see if the context changed (which
would only happen from a thread switch to a different context) and if detected
it inserts a manual MakeCurrent call equivalent.
* It's slow to capture (when this happens - checking is not particularly slow)
and slow to replay, but it's functional which is an improvement.
baldurk