@Override
public void startup(Display display, Map<String, String> properties)
throws Exception {
WTKXSerializer wtkxSerializer = new WTKXSerializer();
window = (Window)wtkxSerializer.readObject(getClass().getResource("file_browsing.wtkx"));
wtkxSerializer.bind(this, FileBrowsing.class);
openSheetButton.getButtonPressListeners().add(new ButtonPressListener() {
@Override
public void buttonPressed(Button button) {