public ItemPage()
        {
            this.InitializeComponent();

            this.navigationHelper = new NavigationHelper(this);
            this.navigationHelper.LoadState += this.NavigationHelper_LoadState;
            this.navigationHelper.SaveState += this.NavigationHelper_SaveState;
        } 
        public PivotPage()
        {
            this.InitializeComponent();

            this.NavigationCacheMode = NavigationCacheMode.Required;

            this.navigationHelper = new NavigationHelper(this);
            this.navigationHelper.LoadState += this.NavigationHelper_LoadState;
            this.navigationHelper.SaveState += this.NavigationHelper_SaveState;

            dataReloadTimer = new DispatcherTimer();
            dataReloadTimer.Tick += DataReloadTimer_Tick;
            dataReloadTimer.Interval = new TimeSpan(0, 1, 0);
            dataReloadTimer.Start();
        }