code: function(binding, e) {
          var keys = ['shift', 'ctrl', 'alt'],
              i = 0,
              len = keys.length,
              val, key;
  
          for (; i < len; ++i){
              key = keys[i];
              val = binding[key];
              if (!(val === undefined || (val === e[key + 'Key']))) {
                  return false;
              }
          }
          return true;
      }
docs: Check if the modifiers on the event match those on the binding
  @private
  @param {Object} binding
  @param {Ext.EventObject} event
  @return {Boolean} True if the event matches the binding