The SendMessageTimeout function sends the specified message to a window or windows. The function calls the window procedure for the specified window and, if the specified window belongs to a different thread, does not return until the window procedure has processed the message or the specified time-out period has elapsed. If the window receiving the message belongs to the same queue as the current thread, the window procedure is called directly ¾ the time-out value is ignored.
LRESULT SendMessageTimeout(
| HWND hWnd, | // handle of destination window |
| UINT Msg, | // message to send |
| WPARAM wParam, | // first message parameter |
| LPARAM lParam, | // second message parameter |
| UINT fuFlags, | // how to send the message |
| UINT uTimeout, | // time-out duration |
| LPDWORD lpdwResult | // return value for synchronous call |
| ); |
Parameters
hWnd
Identifies the window whose window procedure will receive the message. If this parameter is HWND_TOPMOST, the message is sent to all top-level windows in the system, including disabled or invisible unowned windows.
Msg
Specifies the message to be sent.
wParam
Specifies additional message-specific information.
lParam
Specifies additional message-specific information.
fuFlags
Specifies how to send the message. This parameter can be a combination of the following values:
| Value | Meaning |
| SMTO_ABORTIFHUNG | Returns without waiting for the time-out period to elapse if the receiving process appears to be in a "hung" state. |
| SMTO_BLOCK | Prevents the calling thread from processing any other requests until the function returns. |
| SMTO_NORMAL | The calling thread is not prevented from processing other requests while waiting for the function to return. |
uTimeout
Specifies the duration, in milliseconds, of the time-out period.
lpdwResult
Specifies the result of the message processing and depends on the message sent.
Return Values
If the function succeeds, the return value is TRUE.
If the function fails, the return value is FALSE. To get extended error information, call GetLastError.
See Also
InSendMessage, PostMessage, SendDlgItemMessage, SendMessage, SendMessageCallback, SendNotifyMessage