private void EditVehicle()
        {
            String     vehicleRegNo = listBoxFleetList.SelectedItem.ToString();
            ClsVehicle lcVehicle    = ClsRentVehicleFleet.FleetList[vehicleRegNo];

            lcVehicle.ViewEditVehicle();
            UpdateVehicleFleetList();
        }
        private void AddVehicle()
        {
            ClsVehicle lcVehicle = new ClsVehicle();

            if (lcVehicle != null && lcVehicle.ViewEditVehicle())
            {
                ClsRentVehicleFleet.FleetList.Add(lcVehicle.RegistrationNumber, lcVehicle);
                UpdateVehicleFleetList();
            }
        }