function hide_menu() {
	document.getElementById('menu_college').style.visibility = "hidden" ;
	document.getElementById('menu_activites').style.visibility = "hidden" ;
	document.getElementById('menu_anciens').style.visibility = "hidden" ;
}function show_college() {
	document.getElementById('menu_college').style.visibility = "visible" ;
	document.getElementById('menu_activites').style.visibility = "hidden" ;
	document.getElementById('menu_anciens').style.visibility = "hidden" ;
}function show_activites() {
	document.getElementById('menu_college').style.visibility = "hidden" ;
	document.getElementById('menu_activites').style.visibility = "visible" ;
	document.getElementById('menu_anciens').style.visibility = "hidden" ;
}function show_anciens() {
	document.getElementById('menu_college').style.visibility = "hidden" ;
	document.getElementById('menu_activites').style.visibility = "hidden" ;
	document.getElementById('menu_anciens').style.visibility = "visible" ;
}
function popup(url) {
	var hauteur =500;
	var largeur =528;
	var top = (screen.height-hauteur)/2;
	var left = (screen.width-largeur)/2;
	window.open(url,"","top="+top+",left="+left+",width="+largeur+",height="+hauteur);
 }