code: public Table newHeading()
      {
          newBlock("th");
          if (_defaultHead!=null)
          {
              cell.setAttributesFrom(_defaultHead);
              if (_defaultHead.size()>0)
                  cell.add(_defaultHead.contents());
          }
          return this;
      }
docs: /* Create a new Heading in the current row.
  Adds to the table after this call and before next call to newRow,
  newCell or newHeader are added to the cell.