function ouverture_sousmenu(id){
	document.getElementById(id).style.visibility = 'visible';
	document.getElementById(id).style.display = 'block';
}
function fermeture_sousmenu(id){
	document.getElementById(id).style.visibility = 'hidden';
	document.getElementById(id).style.display = 'none';
	
	document.getElementById(id).onmouseover = function(){
		document.getElementById(id).style.visibility = 'visible';
		document.getElementById(id).style.display = 'block';
	}
	document.getElementById(id).onmouseout = function(){
		document.getElementById(id).style.visibility = 'hidden';
		document.getElementById(id).style.display = 'none';
	}
}