code: function(e, cal) {
          var target;
          if (e) {
              target = Event.getTarget(e);
          } else {
              target = this;
          }
  
          while (target.tagName && target.tagName.toLowerCase() != "td") {
              target = target.parentNode;
              if (!target.tagName || target.tagName.toLowerCase() == "html") {
                  return;
              }
          }
  
          if (Dom.hasClass(target, cal.Style.CSS_CELL_SELECTABLE)) {
              Dom.addClass(target, cal.Style.CSS_CELL_HOVER);
          }
      }
docs: The event that is executed when the user hovers over a cell
  @method doCellMouseOver
  @param {DOMEvent} e The event
  @param {Calendar} cal A reference to the calendar passed by the Event utility