The WM_CANCELMODE message is sent to cancel certain modes, such as mouse capture. For example, the system sends this message to the active window when a dialog box or message box is displayed. Certain functions also send this message explicitly to the specified window regardless of whether it is the active window. For example, the EnableWindow function sends this message when disabling the specified window.
WM_CANCELMODE
This message has no parameters.
If an application processes this message, it should return zero.
The DefWindowProc function cancels internal processing of standard scroll bar input, cancels internal menu processing, and releases the mouse capture.