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