/**
   * called during app close down to save state
   *
   * @param outState
   */
  public void saveState(SharedPreferences outState) {
    Log.i(TAG, "save state");
    currentBiblePage.saveState(outState);
    currentCommentaryPage.saveState(outState);
    currentDictionaryPage.saveState(outState);
    currentGeneralBookPage.saveState(outState);

    SharedPreferences.Editor editor = outState.edit();
    editor.putString("currentPageCategory", currentDisplayedPage.getBookCategory().getName());
    editor.commit();
  }