Show indicator workaround for Xamarin.Forms.PageIs.IsBusy

MainActivity.cs

// Android MainActivity
using Android.App;
using Android.Content.PM;
using Android.OS;
using AndroidHUD; // https://github.com/redth-org/AndHUD

namespace ThemingDemo.Droid
{
    [Activity(Label = "ThemingDemo", Icon = "@mipmap/icon", Theme = "@style/MainTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
    public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
    {
        internal static MainActivity Instance { get; private set; }

        protected override void OnCreate(Bundle savedInstanceState)
        {
            TabLayoutResource = Resource.Layout.Tabbar;
            ToolbarResource = Resource.Layout.Toolbar;

            base.OnCreate(savedInstanceState);
            Instance = this;
            global::Xamarin.Forms.Forms.Init(this, savedInstanceState);

            // Register message subscription
            Xamarin.Forms.MessagingCenter.Subscribe<Xamarin.Forms.Page, bool>(this, Xamarin.Forms.Page.BusySetSignalName, OnBusySet);

            LoadApplication(new App());
        }

        // Show busy indicator
        int busyCount = 0;
        void OnBusySet(Xamarin.Forms.Page sender, bool enabled)
        {
            busyCount = System.Math.Max(0, enabled ? busyCount + 1 : busyCount - 1);
            if (busyCount == 0)
            {
                AndHUD.Shared.Dismiss(Instance);
            }
            else
            {
                AndHUD.Shared.Show(Instance, "IsBusy ...", maskType: MaskType.Clear);
            }
        }

    }
}

MainWindow.xaml.cs

// WPF MainWindow
using System;
using Xamarin.Forms;
using Xamarin.Forms.Platform.WPF;

namespace ThemingDemo.WPF
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : FormsApplicationPage
    {
        public MainWindow()
        {
            InitializeComponent();

            Forms.Init();

            // Register message subscription
            MessagingCenter.Subscribe<Xamarin.Forms.Page, bool>(this, Xamarin.Forms.Page.BusySetSignalName, OnBusySet);

            LoadApplication(new ThemingDemo.App());
        }

        // Show busy indicator
        int busyCount = 0;
        void OnBusySet(Xamarin.Forms.Page sender, bool enabled)
        {
            busyCount = Math.Max(0, enabled ? busyCount + 1 : busyCount - 1);
            if (busyCount == 0)
            {
                if (System.Windows.Application.Current.MainWindow is FormsWindow window)
                {
                    window.HideContentDialog();
                }
            }
            else
            {
                if (System.Windows.Application.Current.MainWindow is FormsWindow window)
                {
                    window.ShowContentDialog(new FormsContentDialog()
                    {
                        // Use alternative progress indicator
                        //Content = new System.Windows.Controls.ProgressBar() { IsIndeterminate = true, Height = 20 },
                        Content = new Xamarin.Forms.Platform.WPF.Controls.FormsProgressRing() { IsActive = true }, 
                        Title = "IsBusy ..."
                    });
                }
            }
        }
    }
}

UsageSnippet.cs

Application.Current.MainPage.IsBusy = true;
await System.Threading.Tasks.Task.Delay(5000);
Application.Current.MainPage.IsBusy = false;