function    makeVisible(idElem){
  nodeBulle   = document.getElementById(idElem);
  if( nodeBulle != null ){
    idDuDiv     = idElem;
  }
  nodeBulle   = document.getElementById(idElem);
  if( nodeBulle != null ){
    if( nodeBulle.style.visibility != "block") 
      //nodeBulle.style.visibility = "visible";
      nodeBulle.style.display = "block";
      idDuDiv     = idElem;  
    }
}

function    makeInvisible(idElem){
  if( document.getElementById(idElem) != null ){
    //document.getElementById(idElem).style.visibility = "hidden";
    document.getElementById(idElem).style.display = "none";
    idDuDiv     = "";
  }
}