Behavior Scroll to the last GridviewItem when you change the ItemsSource

ScrollToLeftGridViewBehavior.cs

  public class ScrollToLeftGridViewBehavior : DependencyObject, IBehavior
    {
        public DependencyObject AssociatedObject { get; private set; }

        public object ItemsSource
        {
            get { return (object)GetValue(ItemsSourceProperty); }
            set { SetValue(ItemsSourceProperty, value); }
        }

        public static readonly DependencyProperty ItemsSourceProperty =
            DependencyProperty.Register("ItemsSource", typeof(object),
            typeof(ScrollToLeftGridViewBehavior),
            new PropertyMetadata(null, ItemsSourcePropertyChanged));

        private static void ItemsSourcePropertyChanged(object sender,
            DependencyPropertyChangedEventArgs e)
        {
            var behavior = sender as ScrollToLeftGridViewBehavior;
            if (behavior.AssociatedObject == null || e.NewValue == null) return;

            var collection = behavior.ItemsSource as INotifyCollectionChanged;
            if (collection != null)
            {
                collection.CollectionChanged += (s, args) =>
                {
                    var scrollViewer = behavior.AssociatedObject
                                               .GetFirstDescendantOfType<ScrollViewer>();
                    scrollViewer.ChangeView( scrollViewer.ActualWidth> scrollViewer.ExtentWidth ? 0 :scrollViewer.ExtentWidth-60, null, null);
                };
            }
        }

        public void Attach(DependencyObject associatedObject)
        {
            var control = associatedObject as GridView;
            if (control == null)
                throw new ArgumentException(
                    "ScrollToBottomGridViewBehavior can be attached only to GridViewView.");

            AssociatedObject = associatedObject;
        }

        public void Detach()
        {
            AssociatedObject = null;
        }
    }