private async void OnDeckDragAnDrop(DeckInformation parent, DeckInformation child) { try { deckListViewModel.DragAnDrop(parent, child, decksView); UpdateNoticeText(); } catch (DeckRenameException ex) { if (ex.Error == DeckRenameException.ErrorCode.ALREADY_EXISTS) { await UIHelper.ShowMessageDialog("A deck with the same name already exists."); return; } if (ex.Error == DeckRenameException.ErrorCode.FILTERED_NOSUBDEKCS) { await UIHelper.ShowMessageDialog("A \"Custom Study Deck\" can't become a parent deck."); return; } } catch { await UIHelper.ShowMessageDialog("Unexpected error."); return; } }