BackDrop control does not Initialize SurfaceLoader

[darenm]

If the BackDrop control is used prior to some other object initializing the SurfaceLoader with the appropriate Compositor, an exception is thrown. I added the following to the BackDrop constructor:

        public BackDrop()
        {
            m_rootVisual = ElementCompositionPreview.GetElementVisual(this as UIElement);
            Compositor = m_rootVisual.Compositor;
            // Ensure the BackDrop control initializes the SurfaceLoader
            // If the BackDrop control is used on it's own, an exception is thrown.
            SurfaceLoader.Initialize(Compositor);

[JuniperPhoton]

You should try to initial SurfaceLoader in your page's constructor.

SurfaceLoader.Initialize(ElementCompositionPreview.GetElementVisual(this).Compositor);

[likuba]

Hey @darenm If this solved your issues, it'd be great if you could make a PR with this update and we'll make sure to take a look and review :)