private void DelBtn_Click(object sender, RoutedEventArgs e)
 {
     if (DataGridSubscribers.SelectedItem != null)
     {
         MainWindow.manager.RemoveFromList(DataGridSubscribers.SelectedItem as Subscriber);
         DataGridSubscribers.SelectedItem = null;
         DataGridSubscribers.ItemsSource  = MainWindow.getManagerSubList();
         MainWindow.BackToList();
     }
 }
 private void DataGridSubscribers_Loaded(object sender, RoutedEventArgs e)
 {
     DataGridSubscribers.ItemsSource = MainWindow.getManagerSubList();
 }