GradientJTextPane as TableCellRenderer with HTML Tooltip

public class GradientTextPane extends JTextPane {

    private transient Position.Bias[] bias = new Position.Bias[1];

    /**
     * Creates new form GradientLabel
     */
    public GradientTextPane() {
        initComponents();
    }

    public void setBgColor(Color bgColor) {
        start = bgColor;
        repaint();
    }

    @Override
    public String getToolTipText(MouseEvent e) {
        String title = super.getToolTipText(e);
        JTextPane editor = (JTextPane) e.getSource();
        if (!editor.isEditable()) {
            Point pt = e.getPoint();
            int pos = editor.getUI().viewToModel(editor, pt, bias);
            if (bias[0] == Position.Bias.Backward && pos > 0) {
                pos--;
            }
            if (pos >= 0 && (editor.getDocument() instanceof HTMLDocument)) {
                HTMLDocument hdoc = (HTMLDocument) editor.getDocument();
                Element elem = hdoc.getCharacterElement(pos);
                if (elem != null) {
                    AttributeSet a = elem.getAttributes();
                    //AttributeSet span = (AttributeSet) a.getAttribute(HTML.Tag.SPAN);
                    if (a != null) {
                        title = (String) a.getAttribute(HTML.Attribute.TITLE);
                    }
                }
            }
        }
        return title;
    }

    @Override
    public void paint(Graphics g) {
        int width = getWidth();
        int height = getHeight();

        colors[0] = start;
        colors[1] = start.brighter();
        colors[2] = start;
        // Create the gradient paint
        //GradientPaint paint = new GradientPaint(0, 0, start, width, height, end, true);

        LinearGradientPaint paint = new LinearGradientPaint(0, 0, 0, getHeight(), dist, colors);

        // we need to cast to Graphics2D for this operation
        Graphics2D g2d = (Graphics2D) g;

        // save the old paint
        Paint oldPaint = g2d.getPaint();

        // set the paint to use for this operation
        g2d.setPaint(paint);

        // fill the background using the paint
        g2d.fillRect(0, 0, width, height);

        // restore the original paint
        g2d.setPaint(oldPaint);

        super.paint(g);
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // //GEN-BEGIN:initComponents
    private void initComponents() {

        setOpaque(true);
    }//
//GEN-END:initComponents    // Variables declaration - do not modify//GEN-BEGIN:variables
    // End of variables declaration//GEN-END:variables
    private Color start;
    float[] dist = {0.0f, 0.5f, 1.0f};
    private Color[] colors = new Color[3];
}