public PieToolTipGenerator getToolTipGenerator() {
        return this.toolTipGenerator;
    }

    /**
     * Sets the tool tip generator and sends a {@link PlotChangeEvent} to all 
     * registered listeners.  Set the generator to <code>null</code> if you 
     * don't want any tool tips.
     *
     * @param generator  the generator (<code>null</code> permitted).
     * 
     * @see #getToolTipGenerator()
     */
    public void setToolTipGenerator(PieToolTipGenerator generator) {
        this.toolTipGenerator = generator;
        fireChangeEvent();
    }

    /**
     * Returns the URL generator.
     *
     * @return The generator (possibly <code>null</code>).
     * 
     * @see #setURLGenerator(PieURLGenerator)
     */
    public PieURLGenerator getURLGenerator() {
        return this.urlGenerator;
    }

    /**
     * Sets the URL generator and sends a {@link PlotChangeEvent} to all 
     * registered listeners.
     *
     * @param generator  the generator (<code>null</code> permitted).
     * 
     * @see #getURLGenerator()
     */
    public void setURLGenerator(PieURLGenerator generator) {
        this.urlGenerator = generator;
        fireChangeEvent();