WM_QUERYENDSESSION The WM_QUERYENDSESSION message is sent when the user chooses to end the session or when an application calls the ExitWindows function. If any application returns zero, the session is not ended. The system stops sending WM_QUERYENDSESSION messages as soon as one application returns zero. After processing this message, the system sends the WM_ENDSESSION message with the wParam parameter set to the results of the WM_QUERYENDSESSION message. A window receives this message through its WindowProc function. LRESULT CALLBACK WindowProc( HWND hwnd, // handle to window WM_QUERYENDSESSION, // the message to send WPARAM wParam, // not used LPARAM lParam // logoff option ); Parameters wParam This parameter is reserved for future use. lParam Specifies whether the user is logging off or shutting down the system. If this parameter includes the ENDSESSION_LOGOFF value, the user if logging off. (Note that this parameter is a bit mask. To test for this value, use a bit-wise operation; do not test for equality.) Windows 2000/XP: If this parameter is zero, the system is shutting down.
The WM_QUERYENDSESSION message is sent when the user chooses to end the session or when an application calls the ExitWindows function. If any application returns zero, the session is not ended. The system stops sending WM_QUERYENDSESSION messages as soon as one application returns zero. After processing this message, the system sends the WM_ENDSESSION message with the wParam parameter set to the results of the WM_QUERYENDSESSION message. A window receives this message through its WindowProc function. LRESULT CALLBACK WindowProc(
HWND hwnd, // handle to window
WM_QUERYENDSESSION, // the message to send
WPARAM wParam, // not used
LPARAM lParam // logoff option
);
Parameters
wParam
This parameter is reserved for future use.
lParam
Specifies whether the user is logging off or shutting down the system. If this parameter includes the ENDSESSION_LOGOFF value, the user if logging off. (Note that this parameter is a bit mask. To test for this value, use a bit-wise operation; do not test for equality.)
Windows 2000/XP: If this parameter is zero, the system is shutting down.