public Widget getInstance() { Window win = new Window(); /* <checkbox label="Apple" onCheck="doChecked()" /> */ Checkbox comp = new Checkbox(); comp.setLabel("Apple"); comp.addEventListener( Events.ON_CHECK, new EventListener() { public void onEvent(Event event) { JavaScriptObject nEvent = event.getNativeEvent(); System.out.println(">>checkbox onCheck"); System.out.println("data : " + getJSONString(nEvent)); } }); win.add(comp); return win; }