function menu() {
	var l = document.getElementsByTagName('img');
	for(i=0; i < l.length; i++) {
		if (l[i].className=='bt') {
			l[i].onmouseover = function() {return this.src='/menu/_'+this.getAttribute('id')+'.png';};
			l[i].onmouseout = function() {return this.src='/menu/'+this.getAttribute('id')+'.png';};
			l[i].onclick = function() {this.blur();};
		}
	}
}
window.onload=menu;