function displaymenu(el){
	hidemenu();
	var ul = getChildNodesByTag(el.parentNode,'UL');
	if(ul.length > 0){
		ul[0].style.display = 'block';
		el.className = 'menu_actif';
	}
}

function hidemenu(){
	var ul = document.getElementById('main_menu');
	var li = getChildNodesByTag(ul,'LI');
	for(i=0; i < li.length; i++){
		var menu = li[i];
		var a = getChildNodesByTag(menu,'A');
		a[0].className = 'menu_inactif';
		var smenus = getChildNodesByTag(menu,'UL');
		if(smenus.length > 0){
			smenus[0].style.display = 'none';
		}
	}
}

function getChildNodesByTag(el,tag){
	childs = el.childNodes;
	var bytag = [];
	var a = 0;
	for(b=0;b<childs.length;b++){
		if(childs[b].tagName==tag){
			bytag[a] = childs[b];
			a++;
		}
	}
	return bytag;
}