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;}