private void OnModifyLibrarian(object sender, RoutedEventArgs e)
 {
     if (LibrariansTable.SelectedItem != null)
     {
         AdminUserView  selectedLibrarian = LibrariansTable.SelectedItem as AdminUserView;
         ModifyUserPage modifyLibrarian   = new ModifyUserPage(selectedLibrarian.LibrarianID);
         modifyLibrarian.ShowDialog();
         UpdateTable();
     }
 }
        private void OnDeleteLibrarian(object sender, RoutedEventArgs e)
        {
            if (LibrariansTable.SelectedItem != null)
            {
                MessageBoxResult result = MessageBox.Show(SDM.Strings.DELETE_LIBRARIAN_CONFIRMATION_TEXT,
                                                          SDM.Strings.ATTENTION_TEXT, MessageBoxButton.YesNo);

                switch (result)
                {
                case MessageBoxResult.Yes:
                    AdminUserView selectedLibrarian = LibrariansTable.SelectedItem as AdminUserView;
                    Admin         lib = (Admin)SDM.CurrentUser;
                    lib.DeleteLibrarian(selectedLibrarian.LibrarianID);
                    UpdateTable();
                    break;

                case MessageBoxResult.No:
                    break;
                }
            }
        }