Как заставить дополнительную клавиатуру всегда работать в режиме цифр

procedure TForm1.FormCreate(Sender: TObject);
begin
  Application.OnMessage := AppOnMessage;
end;

procedure TForm1.AppOnMessage(var Msg: TMsg; var Handled: Boolean);
var ccode: Word;
begin
  case Msg.Message of
    WM_KEYDOWN, WM_KEYUP:
      begin
        if (GetKeyState(VK_NUMLOCK) >= 0) //NumLock не включ¸н
          and ((Msg.lparam and $1000000) = 0)
          then
        begin
          ccode := 0;
          case Msg.wparam of
            VK_HOME: ccode := VK_NUMPAD7;
            VK_UP: ccode := VK_NUMPAD8;
            VK_PRIOR: ccode := VK_NUMPAD9;
            VK_LEFT: ccode := VK_NUMPAD4;
            VK_CLEAR: ccode := VK_NUMPAD5;
            VK_RIGHT: ccode := VK_NUMPAD6;
            VK_END: ccode := VK_NUMPAD1;
            VK_DOWN: ccode := VK_NUMPAD2;
            VK_NEXT: ccode := VK_NUMPAD3;
            VK_INSERT: ccode := VK_NUMPAD0;
            VK_DELETE: ccode := VK_DECIMAL;
          end;
          if ccode <> 0 then Msg.Wparam := ccode;
        end;
      end;
  end;
end;