code: function (ev) {
          var target = Event.getTarget(ev); 
          // go up looking for a TD with a className with a ygtv prefix
          while (target && !(target.tagName.toUpperCase() == 'TD' && Dom.hasClass(target.parentNode,'ygtvrow'))) { 
              target = Dom.getAncestorByTagName(target,'td'); 
          }
          if (Lang.isNull(target)) { return null; }
          // If it is a spacer cell, do nothing
          if (/\bygtv(blank)?depthcell/.test(target.className)) { return null;}
          // If it has an id, search for the node number and see if it belongs to a node in this tree.
          if (target.id) {
              var m = target.id.match(/\bygtv([^\d]*)(.*)/);
              if (m && m[2] && this._nodes[m[2]]) {
                  return target;
              }
          }
          return null;
      }
docs: Returns the TD element where the event has occurred
  @method _getEventTargetTdEl
  @private