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.

WM_QUERYENDSESSION 
nSource = (UINT) wParam;    // source of end-session request 
fLogOff = lParam            // logoff flag 
 

Parameters

nSource

Reserved for future use.

fLogOff

Value of lParam. Indicates whether the user is logging off or shutting down the system. Supported values include: ENDSESSION_LOGOFF.

Return Values

If an application can terminate conveniently, it should return TRUE; otherwise, it should return FALSE.

Remarks

By default, the DefWindowProc function returns TRUE for this message.

Windows NT: When an application returns TRUE for this message, it receives the WM_ENDSESSION message and it is terminated, regardless of how the other applications respond to the WM_QUERYENDSESSION message.

Windows 95: After all applications return TRUE for this message, they receive the WM_ENDSESSION and they are terminated.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in winuser.h.

See Also

System Shutdown Overview, System Shutdown Messages, DefWindowProc, ExitWindows, WM_ENDSESSION