private void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
    switch (e.Action)
    {
        case NotifyCollectionChangedAction.Add:
            // ...
            this.UpdateContainerForItem(e.NewStartingIndex);
            return;
        case NotifyCollectionChangedAction.Remove:
            //...
            this.ClearContainerForItemOverride(elements[e.OldStartingIndex], e.OldItems[0] as UIElement);
            return;
        case NotifyCollectionChangedAction.Replace:
            //...
                this.ClearContainerForItemOverride(elements[e.NewStartingIndex], e.OldItems[0] as UIElement);
                elements.RemoveAt(e.NewStartingIndex);
                this.UpdateContainerForItem(e.NewStartingIndex);
            return;
        case NotifyCollectionChangedAction.Reset:
            this.ClearVisualChildren(this.GetItems());
             break;
        default:
            return;
    }
}