code: function(extent, resolutionChanged) {
          var coordSysUnchanged = OpenLayers.Renderer.Elements.prototype.setExtent.apply(this, arguments);
          
          var resolution = this.getResolution(),
              left = -extent.left / resolution,
              top = extent.top / resolution;
  
          // If the resolution has changed, start over changing the corner, because
          // the features will redraw.
          if (resolutionChanged) {
              this.left = left;
              this.top = top;
              // Set the viewbox
              var extentString = "0 0 " + this.size.w + " " + this.size.h;
  
              this.rendererRoot.setAttributeNS(null, "viewBox", extentString);
              this.translate(this.xOffset, 0);
              return true;
          } else {
              var inRange = this.translate(left - this.left + this.xOffset, top - this.top);
              if (!inRange) {
                  // recenter the coordinate system
                  this.setExtent(extent, true);
              }
              return coordSysUnchanged && inRange;
          }
      }
docs: Method: setExtent
  
  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.