code: function() {
          var E = YAHOO.util.Event,
              ua = YAHOO.env.ua;
  
          // IE/Safari 3.1 doesn't fire keypress for arrow/pg keys (non-char keys)
          var arrowEvt = (ua.ie || ua.webkit) ? "keydown" : "keypress";
  
          // - IE/Safari 3.1 doesn't fire keypress for non-char keys
          // - Opera doesn't allow us to cancel keydown or keypress for tab, but 
          //   changes focus successfully on keydown (keypress is too late to change focus - opera's already moved on).
          var tabEvt = (ua.ie || ua.opera || ua.webkit) ? "keydown" : "keypress";
  
          // Everyone likes keypress for Enter (char keys) - whoo hoo!
          E.on(this.yearEl, "keypress", this._handleEnterKey, this, true);
  
          E.on(this.yearEl, arrowEvt, this._handleDirectionKeys, this, true);
          E.on(this.lastCtrl, tabEvt, this._handleTabKey, this, true);
          E.on(this.firstCtrl, tabEvt, this._handleShiftTabKey, this, true);
      }
docs: Attaches DOM listeners for keyboard support.
  Tab/Shift-Tab looping, Enter Key Submit on Year element,
  Up/Down/PgUp/PgDown year increment on Year element
  <p>
  NOTE: MacOSX Safari 2.x doesn't let you tab to buttons and
  MacOSX Gecko does not let you tab to buttons or select controls,
  so for these browsers, Tab/Shift-Tab looping is limited to the
  elements which can be reached using the tab key.
  </p>
  @method applyKeyListeners