((CategoryPlot) signChartPanel.getChart().getPlot()).getDomainAxis().setCategoryLabelPositions(CategoryLabelPositions.UP_90);
((CategoryPlot) signChartPanel.getChart().getPlot()).getRangeAxis().setUpperBound(maxLog2Diff);
((CategoryPlot) signChartPanel.getChart().getPlot()).getRangeAxis().setLowerBound(-maxLog2Diff);
BarChartColorRenderer signRenderer = new BarChartColorRenderer(significanceColors);
signRenderer.setBaseToolTipGenerator(new StandardCategoryToolTipGenerator());
significanceChart.getCategoryPlot().setRenderer(signRenderer);
// add mouse listener
signChartPanel.addChartMouseListener(new ChartMouseListener() {
@Override