docs: 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);
          }
      }