private void initRequiredComponents() {
    fm = getFragmentManager();
    mNavigation = new DirectoryNavigationView(this);

    // add listener for navigation view
    if (mNavigation.listeners.isEmpty()) mNavigation.addonNavigateListener(this);

    // start IconPreview class to get thumbnails if BrowserListAdapter
    // request them
    new IconPreview(this);
  }
  @Override
  public void onDestroy() {
    super.onDestroy();

    if (mNavigation != null) mNavigation.removeOnNavigateListener(this);
  }
 @Override
 public void onUpdatePath(String path) {
   mNavigation.setDirectoryButtons(path);
 }