public double getItemMargin() {
        return this.itemMargin;
    }

    /**
     * Sets the item margin and sends a {@link RendererChangeEvent} to all
     * registered listeners.  The value is expressed as a percentage of the
     * available width for plotting all the bars, with the resulting amount to
     * be distributed between all the bars evenly.
     *
     * @param percent  the new margin.
     *
     * @see #getItemMargin()
     */
    public void setItemMargin(double percent) {
        this.itemMargin = percent;
        fireChangeEvent();