docs: function() {
          var area = 0.0;
          if ( this.components && (this.components.length > 0)) {
              area += Math.abs(this.components[0].getArea());
              for (var i=1, len=this.components.length; i<len; i++) {
                  area -= Math.abs(this.components[i].getArea());
              }
          }
          return area;
      }