code: function(extent, resolutionChanged) {
          var coordSysUnchanged = OpenLayers.Renderer.Elements.prototype.setExtent.apply(this, arguments);
          var resolution = this.getResolution();
      
          var left = (extent.left/resolution) | 0;
          var top = (extent.top/resolution - this.size.h) | 0;
          if (resolutionChanged || !this.offset) {
              this.offset = {x: left, y: top};
              left = 0;
              top = 0;
          } else {
              left = left - this.offset.x;
              top = top - this.offset.y;
          }
  
          
          var org = (left - this.xOffset) + " " + top;
          this.root.coordorigin = org;
          var roots = [this.root, this.vectorRoot, this.textRoot];
          var root;
          for(var i=0, len=roots.length; i<len; ++i) {
              root = roots[i];
  
              var size = this.size.w + " " + this.size.h;
              root.coordsize = size;
              
          }
          // flip the VML display Y axis upside down so it 
          // matches the display Y axis of the map
          this.root.style.flip = "y";
          
          return coordSysUnchanged;
      }
docs: Method: setExtent
  Set the renderer's extent
  
  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.