var lastOpenID = '';

function openMenu(id) {
  var div;
  
  if (id != lastOpenID) {
    if (lastOpenID != '') {
      div = document.getElementById(lastOpenID) ;
      if (div != null) {
        div.style.display = "none" ;
      }
    }
    div = document.getElementById(id) ;
    if (div != null) {    
      lastOpenID = id;
      div.style.display = "" ;
    }
  }
}