WM_TIMECHANGE
An application sends the WM_TIMECHANGE message whenever it updates the system time.
To send this message, call the SendMessage function with the following parameters.
SendMessage(
(HWND) hWnd, // handle to destination window
WM_TIMECHANGE, // message to send
(WPARAM) wParam, // not used; must be zero
(LPARAM) lParam // not used; must be zero
);
Parameters
This message has no parameters.
Return Values
An application should return zero if it processes this message.
Remarks
To send this message to all top-level windows, an application can use the SendMessage function with the hWnd parameter set to HWND_TOPMOST.
Windows 2000/XP: An application should not broadcast this message, because the system will broadcast this message when the application changes the system time.
Windows NT 4.0 and earlier: An application should send this message to all top-level windows after changing the system time.
Windows 95/98/Me: An application should send this message to all top-level windows after changing the system time.