private void Create_New_List_Click(object sender, RoutedEventArgs e)
        {
            currentListName = ShowModalWindow("Введіть назву нового списку");
            tbListName.Text = currentListName;
            if (currentListName == string.Empty)
            {
                return;
            }

            listView.ItemsSource = TaskController.CreateList(currentListName);
        }