code: function(evt) {
          var maploc = this.layer.getLonLatFromViewPortPx(evt.xy); 
          var point = new OpenLayers.Geometry.Point(maploc.lon, maploc.lat);
          if(this.irregular) {
              var ry = Math.sqrt(2) * Math.abs(point.y - this.origin.y) / 2;
              this.radius = Math.max(this.map.getResolution() / 2, ry);
          } else if(this.fixedRadius) {
              this.origin = point;
          } else {
              this.calculateAngle(point, evt);
              this.radius = Math.max(this.map.getResolution() / 2,
                                     point.distanceTo(this.origin));
          }
          this.modifyGeometry();
          if(this.irregular) {
              var dx = point.x - this.origin.x;
              var dy = point.y - this.origin.y;
              var ratio;
              if(dy == 0) {
                  ratio = dx / (this.radius * Math.sqrt(2));
              } else {
                  ratio = dx / dy;
              }
              this.feature.geometry.resize(1, this.origin, ratio);
              this.feature.geometry.move(dx / 2, dy / 2);
          }
          this.layer.drawFeature(this.feature, this.style);
      }
docs: Method: move
  Respond to drag move events
  
  Parameters:
  evt - {Evt} The move event