user32: After handling an internal message give a chance to real message to arrive.

[Dmitry Timoshkov]

Alexandre Julliard <julliard at winehq.org> wrote:

> > The problem is that once Get/PeekMessage handles an internal message it
> > doesn't yield control to another thread and checks the message queue
> > immediately, this misses a sent message from another thread and instead
> > returns a previously posted one. I admit that this is a pure artificial
> > thing that I stumbled upon, but it reveals a real bug in Wine with internal
> > message handling.
> 
> This sounds like a simple race condition. Slowing down message
> processing may make it less likely to happen, but it doesn't fix
> anything.

Yes, it's a race, and it's caused by using internal messages for
synchronization across the threads. Another way to fix this is by
avoiding sending an internal message at all, and probably a test
will show that Windows sends WM_ENABLE message from the source thread.
Would you like to see such a test?

-- 
Dmitry.