procedure TForm1.Timer1Timer(Sender: TObject);
var
 s: string;
 h: HWND;
begin
 h := WindowFromPoint(Mouse.CursorPos);
 SetLength(s, SendMessage(h, WM_GETTEXTLENGTH, 0, 0)+1);
 SendMessage(h, WM_GETTEXT, length(s), Integer(PChar(s)));
 SetLength(s, lStrLen(PChar(s)));
 Label1.Caption := s;
end;