code: function(ev) {
              var eCurrentPanel = YUD.getAncestorByClassName(YUE.getTarget(ev), this.CLASSES.PANEL);
              var nKeyCode = YUE.getCharCode(ev);
              var nLength = this._panels.length;
              if(nKeyCode === 37 || nKeyCode === 38) {
                  for(var i=0;i<nLength;i++) {
                      if((eCurrentPanel === this._panels[i]) && i>0) {
                          this._panels[i-1].firstChild.focus();
                          return;
                      } 
                  }
              }
              if(nKeyCode === 39 || nKeyCode === 40) {
                  for(var i=0;i<nLength;i++) {
                      if((eCurrentPanel === this._panels[i]) && i<nLength-1) {
                          this._panels[i+1].firstChild.focus();
                          return;
                      } 
                  }
              }
          }
docs: Keyboard event handler for keyboard control of the widget
  @method _onKeydown
  @param {Event} ev The Dom event
  @private