JFreeChart chart = createChart(this.dataset, datasetExtension);
ChartPanel panel = new ChartPanel(chart);
panel.setMouseWheelEnabled(true);
//add a selection handler with shift modifier for clicking
RegionSelectionHandler selectionHandler
= new FreeRegionSelectionHandler();
AbstractMouseHandler clickHandler = new MouseClickSelectionHandler(
InputEvent.SHIFT_MASK);
panel.addMouseHandler(selectionHandler);
panel.addMouseHandler(clickHandler);