code: function() {
          this.cache = null;
          if (this.layer && this.layer.events) {
              this.layer.events.un({
                  "beforefeaturesadded": this.handleAdd,
                  "beforefeaturesremoved": this.handleRemove,
                  scope: this
              });            
          }
          return OpenLayers.Strategy.prototype.deactivate.apply(this, arguments);
      }
docs: APIMethod: deactivate
  Deactivate the strategy.  Clear the feature cache.
  
  Returns:
  {Boolean} True if the strategy was successfully deactivated or false if
  the strategy was already inactive.