private static void UpdateItemsLeft()
        {
            var jmlItemsLeft = todoItemList.ItemsLeft();

            itemLeft.InnerHTML = jmlItemsLeft.ToString() + " Items left";
            SetButtonClearCompletedVisible();
            buttonCheckAll.CheckAll = todoItemList.AllComplete();

            if (todoItemList.IsEmpty())
            {
                buttonCheckAll.CheckAll        = false;
                radioButtonQueryItems.Selected = RadioButtonQueryItems.ShowOptions.All;
                footer.Hide();
            }
        }