public void changeButtonStartStop() {
   if (singleton.isThereMeetingToday()) {
     if (singleton.isChronoStarted()) {
       buttonStart.setVisibility(View.INVISIBLE);
       buttonStop.setVisibility(View.VISIBLE);
     } else {
       buttonStart.setVisibility(View.VISIBLE);
       buttonStop.setVisibility(View.INVISIBLE);
     }
   }
 }
  public void changeButtonDirect(int code) {
    if (singleton.isThereMeetingToday()) {
      if (code == VIEW_LAP) {
        buttonBackToMenu.setVisibility(View.VISIBLE);
        buttonDirect.setVisibility(View.INVISIBLE);

      } else {
        buttonBackToMenu.setVisibility(View.INVISIBLE);
        buttonDirect.setVisibility(View.VISIBLE);
      }
    }
  }