private void BtnCategoriesDelete_Click(object sender, EventArgs e)
 {
     if (lbCategories.SelectedItem != null)
     {
         if (FlashcardsMessageBox.YesNo("Are you sure to delete category with all decks and cards?"))
         {
             _categoriesService.Delete(_topic, ((Category)lbCategories.SelectedItem).Id);
             RefreshCategories();
         }
     }
 }
 private void BtnDecksDelete_Click(object sender, EventArgs e)
 {
     if (lbDecks.SelectedItem != null)
     {
         if (FlashcardsMessageBox.YesNo("Are you sure to delete deck with all cards?"))
         {
             var category = (lbCategories.SelectedItem as Category)?.Name;
             _decksService.Delete(_topic, category, ((Deck)lbDecks.SelectedItem).Id);
             RefreshDecks(category);
         }
     }
 }
 private void BtnCardsDelete_Click(object sender, EventArgs e)
 {
     if (lbCards.SelectedItem != null)
     {
         if (FlashcardsMessageBox.YesNo("Are you sure to delete card?"))
         {
             var category = (lbCategories.SelectedItem as Category)?.Name;
             var deck     = (lbDecks.SelectedItem as Deck)?.Name;
             _cardsService.Delete(_topic, category, deck, ((Card)lbCards.SelectedItem).Id);
             RefreshCards(category, deck);
         }
     }
 }