docs: 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;
      }