code: function (lonlat) {
          var px = null; 
          if (this.baseLayer != null) {
              px = this.baseLayer.getViewPortPxFromLonLat(lonlat);
          }
          return px;
      }
docs: APIMethod: getViewPortPxFromLonLat
  
  Parameters:
  lonlat - {<OpenLayers.LonLat>}
  
  Returns:
  {<OpenLayers.Pixel>} An OpenLayers.Pixel which is the passed-in
  <OpenLayers.LonLat>, translated into view port
  pixels by the current base layer.