function swap_menu(elt, num_ul) {

for(i=3; i < 9; i++) {
	var myElement = document.getElementById("menu_li_"+i);
	myElement.className = "normal";
}


    	for (n = elt.nextSibling; n != null; n = n.nextSibling) {
		n.className = "normal";
	}
	for (n = elt.previousSibling; n != null; n = n.previousSibling) {
		n.className = "normal";
	}
	elt.className = "lihover";

	if (document.getElementById("ul_" + num_ul) != null) {
		var noeud = document.getElementById("ul_" + num_ul);
		noeud.style.display="block";
		for (n = noeud.nextSibling; n != null; n = n.nextSibling) {
			if (n.id != null) {
				document.getElementById(n.id).style.display = "none";
			}
		}
		for (n = noeud.previousSibling; n != null; n = n.previousSibling) {
			if (n.id != null) {
				document.getElementById(n.id).style.display = "none";
			}
		}
	} else {
		var noeud = document.getElementById("menu_sec");
		for (var m = noeud.firstChild; m != null; m = m.nextSibling) {
			if (m.id != null) {
				document.getElementById(m.id).style.display = "none";
			}
		}
	}
}