PeekMsg/MsgWaitForMultipleObjects question

Hi,

hopefully somebody familiar with messaging can immediately spot what's wrong
with the code below.

The winmm/midi tests currently in git, using PeekMsg, show that the messages
(from CALLBACK_WINDOW) are almost always immediately available.

Yet the code below, based on MsgWaitFor... times out multiple times
during each test run. Why?
This seems to affect only the messages 3c9/3ca (MOM_DONE and MOM_CALLBACK).

"Bad wait 102 0": 0x102 is WAIT_TIMEOUT. That should never happen.

diff --git a/dlls/winmm/tests/midi.c b/dlls/winmm/tests/midi.c
index 15e02e2..a23fa19 100644
--- a/dlls/winmm/tests/midi.c
+++ b/dlls/winmm/tests/midi.c
@@ -67,8 +67,27 @@ static void test_notification(HWND hwnd, const char* command, UINT m1, DWORD_PTR
     if (hwnd) {
         /* msg.wParam is hmidiout, msg.lParam is the mhdr (or 0) */
         BOOL seen;
+#if 0
         do { seen = PeekMessageA(&msg, hwnd, 0, 0, PM_REMOVE); }
         while(seen && spurious_message(&msg));
+#else
+	seen=0;
+        if (m1 && !seen) {
+          /* We observe intermittent delayed notification.  Perhaps
+           * the OS preempts the player thread after setting MHDR_DONE
+           * or clearing INQUEUE, before calling DriverCallback. */
+          DWORD x;
+          trace("Waiting for delayed message %x from %s\n", m1, command);
+          SetLastError(0xDEADBEEF);
+#if 0
+          x=MsgWaitForMultipleObjects(0, NULL, FALSE, 9999, QS_POSTMESSAGE);
+#else
+          x=MsgWaitForMultipleObjects(0, NULL, FALSE, /*INFINITE*/9999, QS_ALLINPUT);
+#endif
+          ok(x==WAIT_OBJECT_0,"Bad wait %x %d\n",x, GetLastError());
+          seen = PeekMessageA(&msg, hwnd, 0, 0, PM_REMOVE);
+        }
+#endif
         if (seen) {
             trace("Message %x, wParam=%lx, lParam=%lx from %s\n",
                   msg.message, msg.wParam, msg.lParam, command);

Thanks for your help,
    Jörg Höhle