Page scroll fix for jQuery Sortable [http://johnny.github.io/jquery-sortable/ not jQuery UI version]

scrollfix.js

  $('#foo').xsortable({
    onDrag: function ($item, position, _super, event) {
      var $window = $(window);
      var itemTop = $item.offset().top;
      if (itemTop > ($window.scrollTop() + $window.height())) {
        if (!window.lastItemTop || (itemTop > window.lastItemTop)) {
          window.scrollBy(0, 10);
        }
      } else if (itemTop < $window.scrollTop()) {
        if (!window.lastItemTop || (itemTop < window.lastItemTop)) {
          window.scrollBy(0, -10);
        }
      }
      window.lastItemTop = itemTop;
      $item.css(position);
    }
  });