code: @Override
  	public Object getValueAt(final int rowIndex, final int columnIndex)
  	{
  		final Quattro<TL, TR, BL, BR> row = getData().get(rowIndex);
  		switch (columnIndex)
  		{
  			case 0 :
  				return row.getTopLeft();
  			case 1 :
  				return row.getTopRight();
  			case 2 :
  				return row.getBottomLeft();
  			case 3 :
  				return row.getBottomRight();
  			default :
  				return null;
  		}
  	}
docs: {@inheritDoc}