_convertPositionTo: function(d, pos) {

        if(!pos) pos = this.position;
        var mod = d == "absolute" ? 1 : -1;
        var o = this.options, scroll = this.cssPosition == 'absolute' && !(this.scrollParent[0] != document && $.contains(this.scrollParent[0], this.offsetParent[0])) ? this.offsetParent : this.scrollParent, scrollIsRootNode = (/(html|body)/i).test(scroll[0].tagName);