code: function(px) {
          var newPx = px.offset(this.anchor.offset);
          
          //use contentSize if size is not already set
          var size = this.size || this.contentSize;
  
          var top = (this.relativePosition.charAt(0) == 't');
          newPx.y += (top) ? -size.h : this.anchor.size.h;
          
          var left = (this.relativePosition.charAt(1) == 'l');
          newPx.x += (left) ? -size.w : this.anchor.size.w;
  
          return newPx;   
      }
docs: Method: calculateNewPx
  
  Parameters:
  px - {<OpenLayers.Pixel>}
  
  Returns:
  {<OpenLayers.Pixel>} The the new px position of the popup on the screen
  relative to the passed-in px.