docs: function(px) {
          var oldRelativePosition = this.relativePosition;
          this.relativePosition = this.calculateRelativePosition(px);
  
          OpenLayers.Popup.prototype.moveTo.call(this, this.calculateNewPx(px));
          
          //if this move has caused the popup to change its relative position, 
          // we need to make the appropriate cosmetic changes.
          if (this.relativePosition != oldRelativePosition) {
              this.updateRelativePosition();
          }
      }