jQuery.support.allowFixed = function () {
  var isSupported = null;
  if (document.createElement) {
      var el = document.createElement("div");
      if (el && el.style) {
          el.style.width = "1px";
          el.style.height = "1px";
          el.style.position = "fixed";
          el.style.top = "10px";
          var root = document.body;
          if (root && root.appendChild && root.removeChild) {
              root.appendChild(el);
              isSupported = el.offsetTop === 10;
              root.removeChild(el);
          }
          el = null;
      }
  }
  return isSupported;
}