pagecontrol每個tabsheet都是用動態建立的form，節省記憶體

新增一個TPageControl，以及一個TLMDFormDisplay，並將他name命名為fdMainScreen

procedure TForm1.DisplaySimpleForm(ccFormClass:TComponentClass);
begin
  try
    fdMainScreen.UnLoad();
    fdMainScreen.Parent := PageControl1.ActivePage;
    fdMainScreen.Execute(TForm(ccFormClass.Create(Application)));
  except
    exit;
  end;

end;

procedure TForm1.PageControl1Change(Sender: TObject);
begin
  Screen.Cursor := crHourGlass ;
  try
    case PageControl1.ActivePageIndex+1 of
      1 :
        DisplaySimpleForm(TForm2      );
      2 :
        DisplaySimpleForm(TForm3      );
      3 :
        fdMainScreen.UnLoad();
    end;
  finally
    Screen.Cursor := crDefault ;
  end;
end;