private void LoadBookForm()
 {
     if (bookingForm == null)
     {
         bookingForm = new PlaneBookingForm(_planeBookService, _planeService, _cargoService, _customerService);
     }
     bookingForm.MdiParent       = this;
     bookingForm.FormBorderStyle = FormBorderStyle.None;
     this.Size = bookingForm.Size;
     bookingForm.StartPosition = FormStartPosition.Manual;
     bookingForm.Show();
 }
 public MainForm(IPlaneBookService _planeBookService, IPlaneService _planeService, ICargoService _cargoService, ICustomerService _customerService)
 {
     InitializeComponent();
     this._planeBookService = _planeBookService;
     this._planeService     = _planeService;
     this._cargoService     = _cargoService;
     this._customerService  = _customerService;
     this.customerForm      = null;
     this.planeForm         = null;
     this.cargoForm         = null;
     this.bookingForm       = null;
     LoadBookForm();
 }