docs: function(pxBounds) {
          var leftBottomLonLat = this.getLonLatFromOverviewPx({
              x: pxBounds.left,
              y: pxBounds.bottom
          });
          var rightTopLonLat = this.getLonLatFromOverviewPx({
              x: pxBounds.right,
              y: pxBounds.top
          });
          return new OpenLayers.Bounds(leftBottomLonLat.lon, leftBottomLonLat.lat,
                                       rightTopLonLat.lon, rightTopLonLat.lat);
      }