public FrmAddVehicleFeeSetting(UserInfo userInfo, int type, FrmVehicleFeeSetting mainForm)
        {
            //type =0: them moi
            //type=1: cap nhat
            InitializeComponent();
            _userInfo = userInfo;
            _type = type;
            _mainForm = mainForm;

        }
 private void mnuFeeSetting_Click(object sender, EventArgs e)
 {
     FrmVehicleFeeSetting form = new FrmVehicleFeeSetting(_userInfo);
     form.MdiParent = this;
     form.Show();
 }