private static void ItemsSourcePropertyChangedCallback(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
{
var instance = dependencyObject as ListPicker;
if (instance != null)
{
instance.NullItemCollection = new NullItemCollection { SourceCollection = dependencyPropertyChangedEventArgs.NewValue as IList };
instance.NullItem = instance.NullItemCollection.NullObject;
instance.ContentControlSelectedItem.Content = instance.SelectedItem ?? instance.NullItem;
}
}