Xamarin Forms 1.3.1 Navigation.

Application

namespace Mumsee.Mobile.Core.ViewModels
{
	public class AppBootstrapper : ReactiveObject //, IScreen
	{
		// The Router holds the ViewModels for the back stack. Because it's
		// in this object, it will be serialized automatically.
		//public RoutingState Router { get; protected set; }

		public AppBootstrapper ()
		{
			//Router = Router ?? new RoutingState ();
			Locator.CurrentMutable.RegisterConstant (this, typeof(IScreen));

			// Set up Akavache
			// 
			// Akavache is a portable data serialization library that we'll use to
			// cache data that we've downloaded
			BlobCache.ApplicationName = "Mumsee.Mobile";

			// Set up Fusillade
			//
			// Fusillade is a super cool library that will make it so that whenever
			// we issue web requests, we'll only issue 4 concurrently, and if we
			// end up issuing multiple requests to the same resource, it will
			// de-dupe them. We're saying here, that we want our *backing*
			// HttpMessageHandler to be ModernHttpClient.
			Locator.CurrentMutable.RegisterConstant (new NativeMessageHandler (), typeof(HttpMessageHandler));

			// CoolStuff: For routing to work, we need to tell ReactiveUI how to
			// create the Views associated with our ViewModels
			//Locator.CurrentMutable.Register (() => new LoadingView (), typeof(IViewFor<LoadingViewModel>));


			// Kick off to the first page of our app. If we don't navigate to a
			// page on startup, Xamarin Forms will get real mad (and even if it
			// didn't, our users would!)
			//Router.Navigate.Execute (new LoadingViewModel (this));
		}

		public Application CreateMainPage ()
		{
			return new MainApp ();
		}
	}

	public class MainApp : Application
	{
		public MainApp ()
		{
			MainPage = new NavigationPage (new LoadingView ());
		}
	}
} 

The incompatibly is that in 1.3 all Xamarin forms app derive from Application, ReactiveUI can't just return a navigation page. The RoutedViewHost that is normally returned is a NavigationPage