//Нажатие кнопки далее
 public void AddApplicationNextClick(Clientas client)
 {
     if (window.Num.Text.Equals(""))
     {
         MessageBox.Show("Укажите номер заявки!");
     }
     else if (mngRiealtorAgency.Agency.ContainsApplicationNum(int.Parse(window.Num.Text)))
     {
         MessageBox.Show("Заявка с таким номером уже существует!");
     }
     else
     {
         if (window.applicationList.SelectedIndex == 0)                                //Продажа
         {
             SaleWondow sale = new SaleWondow(client, window.Num.Text);
             sale.Owner        = window;
             window.Visibility = Visibility.Hidden;
             sale.ShowDialog();
         }
         else if (window.applicationList.SelectedIndex == 1)                                //Покупка
         {
             PurchaseWindow purchaseWindow = new PurchaseWindow(client, window.Num.Text);
             purchaseWindow.Owner = window;
             window.Visibility    = Visibility.Hidden;
             purchaseWindow.ShowDialog();
         }
         else if (window.applicationList.SelectedIndex == 2)                                //Обмен
         {
             ExchangeWindow exchangeWindow = new ExchangeWindow(client, window.Num.Text);
             exchangeWindow.Owner = window;
             window.Visibility    = Visibility.Hidden;
             exchangeWindow.ShowDialog();
         }
     }
 }
 //Методы
 public SaleWindowController(SaleWondow window)
 {
     this.window = window;
 }