public static void Initialize()
        {
            Fusion.LayoutTracker.Implementation = trackerFunc =>
            {
                var child    = new ReplaySubject <IEnumerable <IControl> >(1);
                var layer    = child.Layer();
                var layerElm = Fusion.Application.MainThread
                               .InvokeAsync(() => layer.NativeHandle)
                               .ToObservable()
                               .Select(elm => (FrameworkElement)elm);

                var content = trackerFunc(new LayoutTracker(layerElm));
                child.OnNext(new[] { content });
                return(layer.WithSize(content.DesiredSize));
            };
        }