* @see #getDataset()
*/
public void setDataset(final PieDataset dataset) {
// if there is an existing dataset, remove the plot from the list of
// change listeners...
final PieDataset existing = this.dataset;
if (existing != null) {
existing.removeChangeListener(this);
}
// set the new dataset, and register the chart as a change listener...
this.dataset = dataset;
if (dataset != null) {