MAUI WindowOverlay

LoadingOverlay.cs

public sealed class LoadingOverlay : WindowOverlay
{
    public LoadingOverlay(IWindow window)
        : base(window)
    {
        AddWindowElement(new LoadingElementOverlay());
        EnableDrawableTouchHandling = true;
    }

    private class LoadingElementOverlay : IWindowOverlayElement
    {
        public void Draw(ICanvas canvas, RectF dirtyRect)
        {
            // Grayed out screen
            canvas.FillColor = Color.FromRgba(0, 0, 0, 64);
            canvas.FillRectangle(dirtyRect);
        }

        public bool Contains(Point point)
        {
            // All touch events are handled by LoadingOverlay
            return true;
        }
    }
}

MainPage.cs

public partial class MainPage
{
    public MainPage()
    {
        InitializeComponent();
    }

    private async void Button_OnClicked(object? sender, EventArgs e)
    {
        var window = GetParentWindow();
        var loading = new LoadingOverlay(window);
        window.AddOverlay(loading);

        await Task.Delay(3000);

        window.RemoveOverlay(loading);
    }
}