code: function() {
          var activated = OpenLayers.Strategy.prototype.activate.call(this);
          if(activated) {
              if(this.layer.visibility === true) {
                  this.start();
              } 
              this.layer.events.on({
                  "visibilitychanged": this.reset,
                  scope: this
              });
          }
          return activated;
      }
docs: Constructor: OpenLayers.Strategy.Refresh
  Create a new Refresh strategy.
  
  Parameters:
  options - {Object} Optional object whose properties will be set on the
  instance.
   
  APIMethod: activate
  Activate the strategy. Register any listeners, do appropriate setup.
  
  Returns:
  {Boolean} True if the strategy was successfully activated.