Código de C# del ejemplo de usar un control en dos sitios

//-----------------------------------------------------------------------------
// Para hacer pruebas con aplicaciones para la Windows Store        (04/Feb/13)
//
// ©Guillermo 'guille' Som, 2013
//-----------------------------------------------------------------------------

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.ApplicationSettings;
using Windows.UI.ViewManagement;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;

// The Blank Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=234238

namespace Prueba_AppStore
{
    /// <summary>
    /// An empty page that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
        }

        /// <summary>
        /// Invoked when this page is about to be displayed in a Frame.
        /// </summary>
        /// <param name="e">Event data that describes how this page was reached.  The Parameter
        /// property is typically used to configure the page.</param>
        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
        }

        // Añadir el botón de configuración al panel inferior    (04/Feb/13)
        // para que siempre esté visible
        // Pero sólo cuando se cierre la AppBar
        private void mainBottomAppBar_Opened(object sender, object e)
        {
            spRow2.Children.Remove(buttonSettings);
            spAppBarSettings.Children.Add(buttonSettings);
        }

        private void mainBottomAppBar_Closed(object sender, object e)
        {
            spAppBarSettings.Children.Remove(buttonSettings);
            spRow2.Children.Add(buttonSettings);
        }

        private void buttonAlarmas_Click(object sender, RoutedEventArgs e)
        {
            mainBottomAppBar.IsOpen = false;

            //... resto del código
        }

        private void button_Clock(object sender, RoutedEventArgs e)
        {
            mainBottomAppBar.IsOpen = false;

            //... resto del código
        }

        private void button_Settings(object sender, RoutedEventArgs e)
        {
            if (ApplicationView.Value != ApplicationViewState.Snapped)
            {
                SettingsPane.Show();
            }
        }

        private void GoBack(object sender, RoutedEventArgs e)
        {
            // para que esté...
        }
    }
}