function getElementsByClassName(className, tag, elm){
	var testClass = new RegExp("(^|\\s)" + className + "(\\s|$)");
	var tag = tag || "*";
	var elm = elm || document;
	var elements = (tag == "*" && elm.all)? elm.all : elm.getElementsByTagName(tag);
	var returnElements = [];
	var current;
	var length = elements.length;
	for(var i=0; i<length; i++){
		current = elements[i];
		if(testClass.test(current.className)){
			returnElements.push(current);
		}
	}
	return returnElements;
}

function niveau(module,lien,menu,classmod){
	cuerpos=getElementsByClassName(classmod);
	liens=document.getElementById(menu).getElementsByTagName("td");

	for(i=0;i<liens.length;i++){
		liens[i].className="";
		cuerpos[i].className=classmod;
	}
	
	document.getElementById(lien).className="selection";
	document.getElementById(module).className+=" visible";
	document.getElementById("corps_onglet").style.background="none";
	document.getElementById("corps_onglet").style.height="100%";
	document.getElementById("corps_onglet").style.background="#e9e9f3"; 
}