code: function () {
          var size = this.map.getSize();
          var tl = this.getLonLatFromViewPortPx({
              x: 0, y: 0
          });
          var br = this.getLonLatFromViewPortPx({
              x: size.w, y: size.h
          });
          
          if ((tl != null) && (br != null)) {
              return new OpenLayers.Bounds(tl.lon, br.lat, br.lon, tl.lat);
          } else {
              return null;
          }
      }
docs: APIMethod: getExtent
  Calculates using px-> lonlat translation functions on tl and br
  corners of viewport
  
  Returns:
  {<OpenLayers.Bounds>} A Bounds object which represents the lon/lat
  bounds of the current viewPort.