docs: private void saveWindowLocation(Point point) {
  		if (point != null) {
  			if (getExtendedState() == Frame.NORMAL) {
  				if (logger.isDebugEnabled()) logger.debug("Saving preference " + PREF_WINDOW_POSITION + "=" + point.x + "," + point.y);
  				this.preferences.put(prefnzPrefix+PREF_WINDOW_POSITION, point.x + ","	+ point.y);
  			} else {
  				if (logger.isDebugEnabled()) logger.debug("Preference " + PREF_WINDOW_POSITION + " not saved, cause window state is not 'normal'.");
  			}
  		}
  	}