WidgetInfo button_2 = panel.getChildrenWidgets().get(1);
// by default "button_1" is displayed
assertTrue(isVisible(button_1));
assertFalse(isVisible(button_2));
// show "button_2"
panel.showWidget(button_2);
assertEditor(
"public class Test implements EntryPoint {",
" public void onModuleLoad() {",
" RootPanel rootPanel = RootPanel.get();",
" DeckPanel panel = new DeckPanel();",