function preload() {
  var file_list = ["make", "demo", "design", "sampleblog"];
  for  (i = 0; i < file_list.length; i++) {
    var tmp_image = new Image();
	tmp_image.src = "/img/top/top_" + file_list[i] + "_on.png";
  }
}
function mouseOver(name, over) {
	target = $("button-" + name);
	if (target != null) {
		if (over) {
			target.src = "/img/top/top_" + name + "_on.png";
		} else {
			target.src = "/img/top/top_" + name + ".png";
		}
	}
}