如何在windows Phone 8.1中显示辅助磁贴的BackContent

在WP8.0中平铺是前后显示的，当来到WP8.1平铺只显示正面时，如何为次要平铺提供背面内容。

在WP 8.0

 StandardTileData NewTileData = new StandardTileData
 {
  BackgroundImage =new Uri(@"Shared/ShellContent/Snow.png",UriKind.Relative),
  Title = ((CheckBox)sender).Content.ToString(),
  Count = 1,
  BackBackgroundImage =new Uri(@"Shared/ShellContent/Snow.png", UriKind.Relative),
  BackTitle = "Back Title",
  BackContent = "Back Content"

};

var secondaryTile = new SecondaryTile(
                "secondaryTileId",
                "Text shown on tile",
                "secondTileArguments",
                new Uri("ms-appx:///Assets/rainier.jpg", UriKind.Absolute),
                TileSize.Square150x150);
        bool isPinned = await secondaryTile.RequestCreateAsync();