code: function(node, doc) {
          doc = doc || (node) ? Y_DOM._getDoc(node) : Y.config.doc; // perf optimization
          var dv = doc.defaultView,
              pageOffset = (dv) ? dv.pageXOffset : 0;
          return Math.max(doc[DOCUMENT_ELEMENT].scrollLeft, doc.body.scrollLeft, pageOffset);
      }
docs: Amount page has been scroll horizontally
  @method docScrollX
  @return {Number} The current amount the screen is scrolled horizontally.