/// <summary>
 /// Create a new RegisterVehicle and GarageShop object.
 /// </summary>
 public MainWindow()
 {
     InitializeComponent();
     registerVehicle = new RegisterVehicle();
     garageShop      = new GarageShop();
     garageShop.RestoreLists();
     InitializeGUI();
     UpdateGUI();
 }
 /// <summary>
 /// Add a vehicle when button is clicked.
 /// </summary>
 /// <param name="sender"></param>
 /// <param name="e"></param>
 private void btnRegisterVehicle_Click(object sender, RoutedEventArgs e)
 {
     registerVehicle = new RegisterVehicle();
     registerVehicle.ShowDialog();
     if (registerVehicle.DialogResult.HasValue && registerVehicle.DialogResult.Value)
     {
         garageShop.AddVehicle(registerVehicle.Vehicle);
         UpdateGUI();
     }
 }