public boolean saveWindowSize()
   {
      Preferences prefs = Preferences.userNodeForPackage(Joculus.class);

      // window preferences
      prefs.putInt(WINDOW_SIZE_DEFAULT_W_PROPERTY_NAME, window_size_last.width);
      prefs.putInt(WINDOW_SIZE_DEFAULT_H_PROPERTY_NAME, window_size_last.height);

      try
      {
         prefs.flush();
      }
      catch (BackingStoreException ex)
      {
         Joculus.showError(UIStrings.ERROR_WRITE_SETTINGS_FAILED + "\n" + ex.getMessage());
      }
      return true;
   }