Example: Handling Quit

public void handleQuit(ApplicationEvent event) {
    Iterator iterator = WindowList.INSTANCE.iterator();
    while (iterator.hasNext()) {
        Frame next = (Frame) iterator.next();
        next.setVisible(false);
        next.dispose();
    }
    
    RecentFileList.INSTANCE.storeRecentFiles();
    System.exit(0);
}