App.xaml.cs

public App() {
    SetMainPage();
}

        public static async void SetMainPage() {
            Current.MainPage = new TabbedPage {
                Children =
                {
                    new NavigationPage(new StatsPage(GetLatestSessions()))
                    {
                        Title = "Stats",
                        Icon = Device.OnPlatform("tab_stats.png",null,null)
                    },
                    new NavigationPage(new SetupPage()
                    {
                        Title = "Setup",
                        Icon = Device.OnPlatform("tab_setup.png",null,null)
                    },
                    new NavigationPage(new SettingsPage())
                    {
                        Title = "Settings",
                        Icon = Device.OnPlatform("tab_settings.png",null,null)
                    }
                }
            };
            var curPage = Current.MainPage as TabbedPage;
            curPage.CurrentPage = curPage.Children[1];
        }

SetupPage.xaml.cs

. . . .

//Open modal from center page here
private async void someButton_Click(object sender, EventArgs e) {
        ...
        pp = new TrainPage(Convert.ToInt32(revLabel.Text), Convert.ToInt32(cwLabel.Text), Convert.ToInt32(ccwLabel.Text));
        await Navigation.PushModalAsync(pp);
}

StatsPage.xaml.cs

....

        protected override void OnAppearing() {
            System.Diagnostics.Debug.WriteLine("StatsPage OnAppearing entered. . .");
            base.OnAppearing();
        }

TrainPage.xaml.cs

private void SomeButton(object o, EventArgs e) {
     StatsDayPage sp = new StatsDayPage(App.GetSessionsByNumber(App.CurrentSessionNumber - 1), true);
     Navigation.PushModalAsync(sp);
}