private void HandleRemovedItem (object sender, ItemEventArgs e)
{
if (e.Item != Item)
return;
Property = null;
}
private void HandleAddedItem (object sender, ItemEventArgs e)
{
if (e.Item != Item)
return;
var container = Source.Value as IAttachedPropertiesContainer;
Property = container.GetProperty (Item, PropertyName);
}