public static void Show(Wallpaper wallpaper) { IntPtr handler = IntPtr.Zero; Execute.OnUIThread(() => { if (RenderWindow == null) { RenderWindow = new RenderWindow { Wallpaper = wallpaper }; RenderWindow.Show(); } else { RenderWindow.Wallpaper = wallpaper; } handler = new WindowInteropHelper(RenderWindow).Handle; }); HandlerWallpaper.Show(handler); }