[Bug 3930] HOMM shows black screen (sound problem)

http://bugs.winehq.org/show_bug.cgi?id=3930

--- Comment #37 from Jörg Höhle   2010-03-03 11:21:08 ---
I instrumented the MIDI tests in the git tree to use callbacks (it's trivial to
do, the code is already there, just trace(GetCurrentProcessId)) and went for a
surprise.

Both w2k and XP execute all callbacks on the caller's thread!  There a single
exception: midiStreamOut's MOM_DONE is called in the context of some other
thread.

This is especially surprising for MOM_POSITIONCB as one would assume that this
one is invoked asynchronously to the main application which is busy doing
something else.  The only mechanism that comes to mind that would allow this is
QueueUserAPC, i.e. the asynchronous procedure call mechanism.  OTOH it means
that if the app never calls Wait(), the APC never executes.

W98SE on WineTestBot executes all callbacks from a thread unique across all
tests (i.e. it's not started anew with every midiOpen), different from the
caller's.  Is this a system-wide MIDI player thread or one solely dedicated to
executing user callbacks?

OTOH Wine executes MOM_OPEN and MOM_CLOSE on the caller's thread like w2k and
XP, but MOM_DONE and MOM_POSITIONCB from the player thread.