function Active_window_mf: Boolean;
var
  WndHandle: HWND;
  ClassName: array[0..256] of Char;
begin
  Result := False;
  WndHandle := GetForegroundWindow;
  if GetClassName(WndHandle, @ClassName[0], Length(ClassName)) > 0 then
    Result := string(ClassName) = 'SDIMainFrame';
end;