@Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    if (savedInstanceState == null) {
      curFile = new File(getArguments().getString(PATH));
    } else {
      curFile = new File(savedInstanceState.getString(PATH));
    }

    pageBuilder.prepare(curFile);
  }
 @Override
 public void onSaveInstanceState(Bundle outState) {
   outState.putString(PATH, curFile.getAbsolutePath());
   super.onSaveInstanceState(outState);
 }