code: function(extent, resolutionChanged) {
          this.extent = extent.clone();
          if (this.map.baseLayer && this.map.baseLayer.wrapDateLine) {
              var ratio = extent.getWidth() / this.map.getExtent().getWidth(),
                  extent = extent.scale(1 / ratio);
              this.extent = extent.wrapDateLine(this.map.getMaxExtent()).scale(ratio);
          }
          if (resolutionChanged) {
              this.resolution = null;
          }
          return true;
      }
docs: Method: setExtent
  Set the visible part of the layer.
  
  Resolution has probably changed, so we nullify the resolution
  cache (this.resolution) -- this way it will be re-computed when
  next it is needed.
  We nullify the resolution cache (this.resolution) if resolutionChanged
  is set to true - this way it will be re-computed on the next
  getResolution() request.
  
  Parameters:
  extent - {<OpenLayers.Bounds>}
  resolutionChanged - {Boolean}
  
  Returns:
  {Boolean} true to notify the layer that the new extent does not exceed
  the coordinate range, and the features will not need to be redrawn.
  False otherwise.