private void drawHorzGridLine(final Graphics2D g2d, final int row, final int col, final int colSpan) {
    // protect against invalid constraints
    if (col < 0 || col+colSpan >= myVertGridLines.length || row < 0 || row >= myHorzGridLines.length) return;
    g2d.drawLine(myVertGridLines [col]+4,
                 myHorzGridLines [row],
                 myVertGridLines [col + colSpan]-4,
                 myHorzGridLines [row]);
  }
private void drawHorzGridLine(final Graphics2D g2d, final int row, final int col, final int colSpan)