function hide(aCacher) {
	forceClass(aCacher, 'hidden');
}

function eltHasClass(o,className){
  if(!o.className)
    return false;
    return new RegExp('\\b' + className + '\\b').test(o.className)
}

function toggleClass(o, className){
  if(!eltHasClass(o,className)) {
    o.className += ' ' + className;
  } else {
    rmClass(o, className);
  }
}

function addClass(o, className){
  if(!eltHasClass(o,className)) {
    o.className += ' ' + className;
  }
}

function rmClass(o, className){
  o.className = o.className.replace(new RegExp('\\s*\\b' + className + '\\b'),'');
}

function forceClass(o, className) {
  if(!eltHasClass(o,className)) {
    o.className = className;
  }
}

function getId(id) {
  var plop = document.getElementById(id);
  return plop;
}

function showHide(id) {
  toggleClass(getId(id), 'hidden');
}

function visibilityOn (id) {
	rmClass(getId(id), 'hidden');
}

function visibilityOff (id) {
	forceClass(getId(id), 'hidden');
}

function temporisedVisibilityOff(id) {
  string = "visibilityOff('"+id+"');";

  a = setTimeout(string,150);
}