[NumLock]

Код:

LRESULT SendMessage(
    HWND hWnd,	// handle of destination window
    UINT Msg,	// message to send
    WPARAM wParam,	// first message parameter
    LPARAM lParam 	// second message parameter
   );

WM_SETTEXT  
wParam = 0;                     // not used; must be zero 
lParam = (LPARAM)(LPCTSTR)lpsz; // address of window-text string