@Override
public void startup(Display display, Map<String, String> properties)
throws Exception {
ButtonGroup buttonGroup = new ButtonGroup();
buttonGroup.getButtonGroupListeners().add(new ButtonGroupListener() {
@Override
public void selectionChanged(ButtonGroup buttonGroupArgument, Button previousSelection) {
System.out.println("selectionChanged(): previousSelection = " + previousSelection
+ ", selection = " + buttonGroupArgument.getSelection());
}