public Object clone() throws CloneNotSupportedException {

        Plot clone = (Plot) super.clone();
        // private Plot parent <-- don't clone the parent plot, but take care
        // childs in combined plots instead
        if (this.datasetGroup != null) {
            clone.datasetGroup
                = (DatasetGroup) ObjectUtilities.clone(this.datasetGroup);
        }
        clone.drawingSupplier
            = (DrawingSupplier) ObjectUtilities.clone(this.drawingSupplier);
        clone.listenerList = new EventListenerList();
        return clone;