[Xcb] [PATCH 2/3] Do not block when calling reply() multiple times.

[Barton C Massey]

I know of no strong engineering reason why the fact that all
cookies have sequence numbers should be opaque.  It would
obviously be a bad mistake if people tried to do things with
sequence ordering or something, but just passing them around
generically isn't going to hurt anything.  The fundamental
problem here as I see it is simply that C has no type
language for "cookie.sequence is an integer, but not one that
outside callers should ever read or write".  So we let
engineering discipline substitute for the type system.

	Bart