function popup(montre,cache1,cache2) { 

   if (!(document.all || document.layers)) return;

   if (null != document.all) { // If IE4+
      document.all[cache1].style.visibility = "hidden";
      document.all[cache2].style.visibility = "hidden";
      document.all[montre].style.visibility = "visible";
      } 
    else { // If NN4+
      document.layers[montre].visibility = "visible";
      document.layers[cache1].visibility = "hidden";
      document.layers[cache2].visibility = "hidden";
    }
}