The WM_QUEUESYNC message is sent by a computer-based training (CBT) application to separate user-input messages from other messages sent through the WH_JOURNALPLAYBACK hook procedure.
WM_QUEUESYNC wParam = 0; // not used, must be zero lParam = 0; // not used, must be zero
This message has no parameters.
A CBT application should return zero if it processes this message.
Whenever a CBT application uses the WH_JOURNALPLAYBACK hook procedure, the first and last messages are WM_QUEUESYNC. This allows the CBT application to intercept and examine user-initiated messages without doing so for events that it sends.
If an application specifies a NULL window handle, the message is posted to the message queue of the active window.