[Bug] Xamarin.UWP CarouselPage OnAppearing() bug

[jessiezh0320]

Set "Current Page" to not the first page, why do dialog in other pages also pop up?

Steps to Reproduce

1. Create a blank xamarin form demo .
2. Create a page Home which extends CarouselPage :

Home.xaml.cs

public partial class Home : CarouselPage 
    {
        public Home()
        {
            Children.Insert(0, new CarPage1());
            Children.Insert(1, new CarPage2());
            Children.Insert(2, new CarPage3());
            CurrentPage = Children[1];

            InitializeComponent();
        }
    }

Home.xaml

<?xml version="1.0" encoding="utf-8" ?> 
<CarouselPage  xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="UwpApp1024.Home">

</CarouselPage>

3.Create three Contentpage (CarPage1, CarPage2 and CarPage3) and add the following functions：

CarPage1.xaml.cs

    public partial class CarPage1 : ContentPage 
    {
        public CarPage1()
        {
            InitializeComponent();
        }

        protected override void OnAppearing()
        {
            base.OnAppearing();
            DisplayAlert("Page1", null, "ok");
        }
    }

CarPage2.xaml.cs

    public partial class CarPage2 : ContentPage 
    {
        public CarPage2()
        {
            InitializeComponent();
        }

        protected override void OnAppearing()
        {
            base.OnAppearing();
            DisplayAlert("Page2", null, "ok");
        }
    }

CarPage3.xaml.cs

    public partial class CarPage3 : ContentPage 
    {
        public CarPage3()
        {
            InitializeComponent();
        }

        protected override void OnAppearing()
        {
            base.OnAppearing();
            DisplayAlert("Page3", null, "ok");
        }
    }

4. modify the following code in App.xaml.cs:

     MainPage = new NavigationPage(new Home());
   

5.Deploy the app to uwp, you could find that Page2 alert show, then click ok, why Page1 alert show?

Expected Behavior

After Page2 alert show, then click ok button, the Page2 could display normally.
And above code works on android.

Actual Behavior