code: function (newOptions, reinitialize) {
          var singleTileChanged = newOptions.singleTile !== undefined && 
              newOptions.singleTile !== this.singleTile;
          OpenLayers.Layer.HTTPRequest.prototype.addOptions.apply(this, arguments);
          if (this.map && singleTileChanged) {
              this.initProperties();
              this.clearGrid();
              this.tileSize = this.options.tileSize;
              this.setTileSize();
              this.moveTo(null, true);
          }
      }
docs: APIMethod: addOptions
  
  Parameters:
  newOptions - {Object}
  reinitialize - {Boolean} If set to true, and if resolution options of the
  current baseLayer were changed, the map will be recentered to make
  sure that it is displayed with a valid resolution, and a
  changebaselayer event will be triggered.