var i = 0;

// 画像の先読み
var imgs = new Array();
imgs[0] = new Array();
imgs[1] = new Array();
imgs[0][i] = new Image(); imgs[0][i++].src="img/top_menu_about_b.jpg";
imgs[0][i] = new Image(); imgs[0][i++].src="img/top_menu_schedule_b.jpg";
imgs[0][i] = new Image(); imgs[0][i++].src="img/top_menu_event_b.jpg";
imgs[0][i] = new Image(); imgs[0][i++].src="img/top_menu_class_b.jpg";
imgs[0][i] = new Image(); imgs[0][i++].src="img/top_menu_rental_b.jpg";
imgs[0][i] = new Image(); imgs[0][i++].src="img/top_menu_access_b.jpg";
imgs[0][i] = new Image(); imgs[0][i++].src="img/top_menu_contact_b.jpg";
imgs[0][i] = new Image(); imgs[0][i++].src="img/top_menu_link_b.jpg";

var mi;

function init(){
	var tmp = document.getElementById("top_menu_list");
	mi = tmp.getElementsByTagName("img");
	for( i = 0; i < mi.length; i++ ){
		imgs[1][i] = new Image(); imgs[1][i].src = mi[i].src;
		mi[i].setAttribute("onmouseover", "rollover("+i+", 0)");
		mi[i].setAttribute("onmouseout",  "rollover("+i+", 1)" );
	}
}

function rollover(num, flag){
	mi[num].src = imgs[flag][num].src;
}