this.renderAsPercentages = false;
        
        // set the default item label positions, which will only be used if 
        // the user requests visible item labels...
        ItemLabelPosition p = new ItemLabelPosition(ItemLabelAnchor.CENTER, 
                TextAnchor.CENTER);
        setBasePositiveItemLabelPosition(p);
        setBaseNegativeItemLabelPosition(p);
        setPositiveItemLabelPositionFallback(null);
        setNegativeItemLabelPositionFallback(null);