public static void SetApplicationBar(DependencyObject obj, ApplicationBar value)
        {
            if (!(obj is Page)) { throw new InvalidOperationException("AppbarHost is must owned by Page"); } // TODO: メッセージ怪しい
            var rootPage = obj as Page;

            // Check old ApplicationBar
            if (GetApplicationBar(obj) != null)
            {
                // Detatch Events
                var oldAppBar = GetApplicationBar(obj);
                oldAppBar.Uninitialize();
            }

            // Initialize ApplicationBar
            value.Initialize(rootPage);

            // Set attached property
            obj.SetValue(ApplicationBarProperty, value);
        }