protected override void OnModelChanged(VisualElement oldModel, VisualElement newModel)
        {
            base.OnModelChanged(oldModel, newModel);

            // this is a ViewGroup - so should be able to load an AXML file and FindView<>
            var activity = this.Context as Activity;

            var auth = new OAuth2Authenticator(
                clientId: "574134802616730", // your OAuth2 client id
                scope: "email,user_about_me", // the scopes for the particular API you're accessing, delimited by "+" symbols
                authorizeUrl: new Uri("https://m.facebook.com/dialog/oauth/"), // the auth URL for the service
                redirectUrl: new Uri("https://www.cautom.com/SocialAuth/FBLogin/")); // the redirect URL for the service

            auth.Completed += (sender, eventArgs) =>
            {
                if (eventArgs.IsAuthenticated)
                {
                    //App.SuccessfulLoginAction.Invoke();
                    // Use eventArgs.Account to do wonderful things
                    //App.SaveToken(eventArgs.Account.Properties["access_token"]);
                    string accessToken = eventArgs.Account.Properties["access_token"];
                    new FacebookLoginWebView().fetchUserInfoFromAccessToken(accessToken);
                }
                else
                {
                    // The user cancelled
                }
            };

            activity.StartActivity(auth.GetUI(activity));
        }

        protected override void OnElementChanged(VisualElement oldElement, VisualElement newElement)
        {
            base.OnElementChanged(oldElement, newElement);

            if (oldElement != null)
            {
                oldElement.PropertyChanged -= this.HandleMasterDetailPagePropertyChanged;
                oldElement.PropertyChanging -= this.HandleMasterDetailPagePropertyChanging;
            }

            if (newElement != null)
            {
                newElement.PropertyChanged += this.HandleMasterDetailPagePropertyChanged;
                newElement.PropertyChanging += this.HandleMasterDetailPagePropertyChanging;
            }

            if (oldElement == null && newElement != null)
            {
                this.SetFitsSystemWindows(true);

                var activity = (Activity)this.Context;

                this.actionBarDrawerToggle = new CustomActionBarDrawerToggle(this, activity, this) { DrawerIndicatorEnabled = true };

                this.ActionBar.SetDisplayHomeAsUpEnabled(true);
                this.ActionBar.SetHomeButtonEnabled(true);

                this.actionBarDrawerToggle.SyncState();

                this.BindNavigationEventHandlers();
            }
        }

		protected override void OnModelChanged (VisualElement oldModel, VisualElement newModel)
		{
			base.OnModelChanged (oldModel, newModel);

			// this is a ViewGroup - so should be able to load an AXML file and FindView<>
			var activity = this.Context as Activity;

			var auth = new OAuth2Authenticator (
				clientId: App.Instance.OAuthSettings.ClientId, // your OAuth2 client id
				scope: App.Instance.OAuthSettings.Scope, // The scopes for the particular API you're accessing. The format for this will vary by API.
				authorizeUrl: new Uri (App.Instance.OAuthSettings.AuthorizeUrl), // the auth URL for the service
				redirectUrl: new Uri (App.Instance.OAuthSettings.RedirectUrl)); // the redirect URL for the service

			auth.Completed += (sender, eventArgs) => {
				if (eventArgs.IsAuthenticated) {
					App.Instance.SuccessfulLoginAction.Invoke();
					// Use eventArgs.Account to do wonderful things
					App.Instance.SaveToken(eventArgs.Account.Properties["access_token"]);
				} else {
					// The user cancelled
				}
			};

			activity.StartActivity (auth.GetUI(activity));
		}

        public void SetElement(VisualElement element)
        {
            var oldElement = this.Element;

            if (oldElement != null)
                oldElement.PropertyChanged -= HandlePropertyChanged;

            this.Element = element;
            if (this.Element != null)
            {

                this.Element.PropertyChanged += HandlePropertyChanged;
            }

            ViewGroup.RemoveAllViews();
            Tracker = new VisualElementTracker(this);

            Packager = new VisualElementPackager(this);
            Packager.Load();

            UseCompatPadding = true;

            SetContentPadding((int)TheView.Padding.Left, (int)TheView.Padding.Top,
                   (int)TheView.Padding.Right, (int)TheView.Padding.Bottom);

            Radius = TheView.CornerRadius;
            SetCardBackgroundColor(TheView.BackgroundColor.ToAndroid());

            if (ElementChanged != null)
                ElementChanged(this, new VisualElementChangedEventArgs(oldElement, this.Element));
        }

        /// <summary>
        /// Setup our SwipeRefreshLayout and register for property changed notifications.
        /// </summary>
        /// <param name="element">Element.</param>
        public void SetElement(VisualElement element)
        {
            var oldElement = Element;

            //unregister old and re-register new
            if (oldElement != null)
                oldElement.PropertyChanged -= HandlePropertyChanged;

            Element = element;
            if (Element != null)
            {
                UpdateContent();
                Element.PropertyChanged += HandlePropertyChanged;
            }

            if (!init)
            {
                init = true;
                //sizes to match the forms view
                //updates properties, handles visual element properties
                Tracker = new VisualElementTracker(this);
                SetOnRefreshListener(this);
            }

            UpdateColors();
            UpdateIsRefreshing();
            UpdateIsSwipeToRefreshEnabled();

            if (ElementChanged != null)
                ElementChanged(this, new VisualElementChangedEventArgs(oldElement, this.Element));
        }

 async protected override void Invoke(VisualElement visual)
 {
     visual.AnchorX = Anchor.X;
     visual.AnchorY = Anchor.Y;
     await Task.Delay(Delay);
     await visual.ScaleTo(Scale, (uint)Length, Easing);
 }

        public void SetElement(VisualElement element)
        {
            var oldElement = this.Element;

            if (oldElement != null)
            {
                oldElement.PropertyChanged -= this.HandlePropertyChanged;
            }

            this.Element = element;

            if (this.Element != null)
            {
                this.Element.PropertyChanged += this.HandlePropertyChanged;
            }

            this.RemoveAllSubviews();
            this.Tracker = new VisualElementTracker(this);

            this.Packager = new VisualElementPackager(this);
            this.Packager.Load();

            this.SetContentPadding((int)TheView.Padding.Left, (int)TheView.Padding.Top, (int)TheView.Padding.Right, (int)TheView.Padding.Bottom);

            this.SetCardBackgroundColor(this.TheView.BackgroundColor.ToUIColor());

            if (ElementChanged != null)
            {
                this.ElementChanged(this, new VisualElementChangedEventArgs(oldElement, this.Element));
            }
        }

        public void SetElement(VisualElement element)
        {
            var oldElement = this.Element;

            if (oldElement != null)
            {
                this.HookPropertyChanged(oldElement);
            }

            if (oldElement == null)
            {
                this.Element = element;
                this.UnhookPropertyChanged(this.Element);
                this.Tracker = new VisualElementTracker(this);

                if (this.Control == null)
                {
                    this.Control = this.CreateFloatingActionButton();
                    this.Control.Clickable = true;
                    this.Control.SetOnClickListener(new OnClickListener(x => this.FloatingButton.ExecuteCommand()));

                    this.UpdateColorState();
                    this.UpdateIcon();
                }

                this.AddView(this.Control);
            }

            this.OnElementChanged(new VisualElementChangedEventArgs(oldElement, this.Element));
        }

        public void SetElement(VisualElement element)
        {
            var oldElement = this.Element;

            if (oldElement != null)
                oldElement.PropertyChanged -= HandlePropertyChanged;

            this.Element = element;
            if (this.Element != null) {
                //UpdateContent ();
                this.Element.PropertyChanged += HandlePropertyChanged;
            }

            this.ViewGroup.RemoveAllViews ();
            //sizes to match the forms view
            //updates properties, handles visual element properties
            this.Tracker = new VisualElementTracker (this);

            this.Packager = new VisualElementPackager (this);
            this.Packager.Load ();

            this.UseCompatPadding = true;

            this.SetContentPadding ((int)TheView.Padding.Left, (int)TheView.Padding.Top, (int)TheView.Padding.Right, (int)TheView.Padding.Bottom);

            this.Radius = TheView.CornderRadius;

            this.SetCardBackgroundColor(TheView.BackgroundColor.ToAndroid ());
            if (this.ElementChanged != null)
            {
                this.ElementChanged(this, new VisualElementChangedEventArgs(oldElement, this.Element));
            }
        }

 /// <summary>
 /// Constructor.
 /// </summary>
 /// <param name="element">The element that caused the layout operation.</param>
 /// <param name="other">The list of other elements that were affected by the operation.</param>
 /// <param name="direction">The direction that the layout should be performed in.</param>
 /// <param name="value">The value that the elements will be affected by in the layout direction.</param>
 internal LayoutOperation(VisualElement element, IEnumerable<VisualElement> other, LayoutDirection direction, double value)
 {
     RootElement = element;
     Elements = new [] { element }.Union(other).ToList();
     Direction = direction;
     Value = value;
 }

 public static void AdaptForBinding(VisualElement element, IMvxBindingContextOwner contextOwner)
 {
     var mvxPage = element as IMvxContentPage;
     if (mvxPage != null) {
         contextOwner.BindingContext = new MvxBindingContext();
         contextOwner.BindingContext.DataContext = mvxPage.ViewModel;
     }
 }

        protected override void OnElementChanged(VisualElement oldElement, VisualElement newElement) {
            base.OnElementChanged(oldElement, newElement);

            var fld = typeof(MasterDetailPageRenderer).GetField("detailLayout", BindingFlags.NonPublic | BindingFlags.Instance);
            var fldValue = fld.GetValue(this);
            var p = fld.FieldType.GetProperty("TopPadding", BindingFlags.Public | BindingFlags.Instance);
            p.SetValue(fldValue, 0);
        }

		protected override void OnModelChanged (VisualElement oldModel, VisualElement newModel)
		{
			base.OnModelChanged (oldModel, newModel);

			var tableView = Control as global::Android.Widget.ListView;
			tableView.DividerHeight = 0;
			tableView.SetBackgroundColor (new global::Android.Graphics.Color(0x2C, 0x3E, 0x50));
		}

		public FocusEventArgs(VisualElement visualElement, bool isFocused)
		{
			if (visualElement == null)
				throw new ArgumentNullException("visualElement");

			VisualElement = visualElement;
			IsFocused = isFocused;
		}

		static Task<bool> ColorAnimation(VisualElement element, string name, Func<double, Color> transform, Action<Color> callback, uint length, Easing easing)
		{
			easing = easing ?? Easing.Linear;
			var taskCompletionSource = new TaskCompletionSource<bool>();

			element.Animate<Color>(name, transform, callback, 16, length, easing, (v, c) => taskCompletionSource.SetResult(c));
			return taskCompletionSource.Task;
		}

        /// <summary>
        /// Gets the services page.
        /// </summary>
        /// <param name="mainPage">The main page.</param>
        /// <returns>Content Page.</returns>
        private static ContentPage GetServicesPage(VisualElement mainPage)
        {
            var services = new ContentPage { Title = "Services" };
            var lstServices = new ListView
            {
                ItemsSource = new List<string>() {
                    "TextToSpeech",
                    "DeviceExtended",
                    "PhoneService",
                    "GeoLocator",
                    "Camera",
                    "Accelerometer",
                    "Display",
                    "Cache",
                    "Sound"
                }
            };

            lstServices.ItemSelected += async (sender, e) =>
            {
                switch (e.SelectedItem.ToString().ToLower())
                {
                    case "texttospeech":
                        await mainPage.Navigation.PushAsync(new TextToSpeechPage());
                        break;
                    case "deviceextended":
                        await mainPage.Navigation.PushAsync(new ExtendedDeviceInfoPage(Resolver.Resolve<IDevice>()));
                        break;
                    case "phoneservice":
                        await mainPage.Navigation.PushAsync(new PhoneServicePage());
                        break;
                    case "geolocator":
                        await mainPage.Navigation.PushAsync(ViewFactory.CreatePage<GeolocatorViewModel>());
                        break;
                    case "camera":
                        await mainPage.Navigation.PushAsync(ViewFactory.CreatePage<CameraViewModel>());
                        break;
                    case "accelerometer":
                        await mainPage.Navigation.PushAsync(new AcceleratorSensorPage());
                        break;
                    case "display":
                        await mainPage.Navigation.PushAsync(new AbsoluteLayoutWithDisplayInfoPage(Resolver.Resolve<IDisplay>()));
                        break;
                    case "cache":
                        await mainPage.Navigation.PushAsync(ViewFactory.CreatePage<CacheServiceViewModel>());
                        break;
                    case "sound":
                        await mainPage.Navigation.PushAsync(ViewFactory.CreatePage<SoundServiceViewModel>());
                        break;
                    default:
                        break;
                }
            };
            services.Content = lstServices;
            return services;
        }

        protected override void OnModelChanged(VisualElement oldModel, VisualElement newModel)
        {
            base.OnModelChanged (oldModel, newModel);

            // this is a ViewGroup - so should be able to load an AXML file and FindView<>
            var activity = this.Context as Activity;

            var thirdActivity = new Intent (activity, typeof (MyThirdActivity));
            activity.StartActivity (thirdActivity);
        }

 /// <summary>
 /// Gets the or create renderer.
 /// </summary>
 /// <returns>The or create renderer.</returns>
 /// <param name="source">Source.</param>
 public static IVisualElementRenderer GetOrCreateRenderer(VisualElement source)
 {
     var renderer = RendererHelper.GetRenderer (source);
     if (renderer == null) {
         renderer = RendererFactory.GetRenderer (source);
         RendererHelper.SetRenderer (source, renderer);
         renderer = RendererHelper.GetRenderer (source);
     }
     return renderer;
 }

 /// <summary>
 /// Gets the controls page.
 /// </summary>
 /// <param name="mainPage">The main page.</param>
 /// <returns>Content Page.</returns>
 private static ContentPage GetControlsPage(VisualElement mainPage)
 {
     var controls = new ContentPage { Title = "Controls" };
     var lstControls = new ListView
     {
         ItemsSource = new List<string>()
         {
             "Calendar",
             "Autocomplete",
             "Buttons",
             "Labels",
             "Cells",
             "HybridWebView",
             "WebImage",
             "DynamicListView"
         }
     };
     lstControls.ItemSelected += async (sender, e) =>
     {
         switch (e.SelectedItem.ToString().ToLower())
         {
             case "calendar":
                 await mainPage.Navigation.PushAsync(new CalendarPage());
                 break;
             case "autocomplete":
                 await mainPage.Navigation.PushAsync(new AutoCompletePage());
                 break;
             case "buttons":
                 await mainPage.Navigation.PushAsync(new ButtonPage());
                 break;
             case "labels":
                 await mainPage.Navigation.PushAsync(new ExtendedLabelPage());
                 break;
             case "cells":
                 await mainPage.Navigation.PushAsync(new ExtendedCellPage());
                 break;
             case "hybridwebview":
                 await mainPage.Navigation.PushAsync(new CanvasWebHybrid());
                 break;
             case "webimage":
                 await mainPage.Navigation.PushAsync(new WebImagePage());
                 break;
             case "dynamiclistview":
                 await mainPage.Navigation.PushAsync(new Xamarin.Forms.Labs.Sample.Pages.Controls.DynamicList.DynamicListView());
                 break;
             default:
                 break;
         }
     };
     controls.Content = lstControls;
     return controls;
 }

		protected override void OnModelSet (VisualElement model)
		{
			_view = (CalendarView)model;
			base.OnModelSet (model);

			var calendarView = new CalendarMonthView(DateTime.Now, true);

			calendarView.OnDateSelected += (date) => {
				_view.NotifyDateSelected(date);
			};

			base.SetNativeControl (calendarView);
		}