panel.showWidget(button_3);
assertFalse(isVisible(button_1));
assertFalse(isVisible(button_2));
assertTrue(isVisible(button_3));
// move "button_3"
panel.command_MOVE2(button_3, button_2);
assertEditor(
"public class Test implements EntryPoint {",
" public void onModuleLoad() {",
" RootPanel rootPanel = RootPanel.get();",
" DeckPanel panel = new DeckPanel();",