private void AddOrRemoveFav( object sender, TappedRoutedEventArgs e )
{
BookItem B = ( ( sender as FrameworkElement ).DataContext ) as BookItem;
BookStorage BS = new BookStorage();
if ( B.IsFav )
{
BS.RemoveBook( B.Id );
B.IsFav = false;
}
else
{
BS.SaveBook( B.Id, B.Title, B.RecentUpdateRaw, B.LatestSection );
B.IsFav = true;
}
}