* the dataset (<code>null</code> permitted).
*/
public void setDataset(final int index, final XYDataset dataset) {
final XYDataset existing = this.getDataset(index);
if (existing != null) {
existing.removeChangeListener(this);
}
if (index == this.datasets.size()) {
this.datasets.add(index, dataset);
} else {
this.datasets.set(index, dataset);