public Range findRangeBounds(XYDataset dataset) {
        if (dataset != null) {
            Range r = DatasetUtilities.findRangeBounds(dataset, false);
            if (r == null) {
                return null;
            }
            else {
                return new Range(r.getLowerBound() + this.yOffset,
                        r.getUpperBound() + this.blockHeight + this.yOffset);
            }
        }
        else {
            return null;