private int VerifyRealizedRange(ItemsRepeater repeater, CustomItemsSource dataSource)
        {
            int numRealized = 0;

            // trace
            Log.Comment("index:ItemsSourceView:Item");
            for (int i = 0; i < dataSource.Inner.Count; i++)
            {
                var element = repeater.TryGetElement(i);
                if (element != null)
                {
                    var data = ((TextBlock)element).Text;
                    Log.Comment("{0} {1}:[{2}]", i, dataSource.GetAt(i), data);
                    numRealized++;
                }
                else
                {
                    Log.Comment(i + ":[null]");
                }
            }

            // verify
            for (int i = 0; i < dataSource.Inner.Count; i++)
            {
                var element = repeater.TryGetElement(i);
                if (element != null)
                {
                    var data = ((TextBlock)element).Text;
                    Verify.AreEqual(dataSource.GetAt(i).ToString(), data);
                }
            }

            return(numRealized);
        }