获取系统dialog中的某个组

public Object dialog(Object _dialog)
{
    //Object ret;
    DialogRunbase       dialog = _dialog;
    DialogField      dialogField;
    DialogGroup      dialogGroup;
    ;
    //ret = super(_dialog);

    dialogGroup = dialog.getDialogClass("Grp_4");

    dialogGroup2 = dialog.getDialogClass("RightButtonGrp");
    dialogGroup2.visible(false);//隐藏Grp_4
    dialogField = dialog.addField(typeid(ItemId));

    return dialog;
}