code: function(evt) {
          if (evt == null) {
              this.reset();
              return;
          }
  
          var lonLat = this.map.getLonLatFromPixel(evt.xy);
          if (!lonLat) { 
              return;
          }    
          
          var layers = this.findLayers();
          if (layers.length > 0) {
              var infoLookup = {};
              var layer, idx;
              for (var i=0, len=layers.length; i<len; i++) {
                  layer = layers[i];
                  idx = OpenLayers.Util.indexOf(this.map.layers, layer);
                  infoLookup[idx] = layer.getFeatureInfo(lonLat);
              }
              this.callback(infoLookup, lonLat, evt.xy);
          }
      }
docs: Method: handleEvent
  Internal method called when specified event is triggered.
  
  This method does several things:
  
  Gets the lonLat of the event.
  
  Loops through the appropriate hit grid layers and gathers the attributes.
  
  Passes the attributes to the callback
  
  Parameters:
  evt - {<OpenLayers.Event>}