if(parent.frames.length > 0) {
		parent.location.href = location.href;
	}

	if(document.images) {
		img_home = new Image();
		img_home.src = "/images/button_home.gif";
		img_home_over = new Image();
		img_home_over.src = "/images/button_home_over.gif";
		img_history = new Image();
		img_history.src = "/images/button_history.gif";
		img_history_over = new Image();
		img_history_over.src = "/images/button_history_over.gif";
		img_join = new Image();
		img_join.src = "/images/button_join.gif";
		img_join_over = new Image();
		img_join_over.src = "/images/button_join_over.gif";
	}

	function mouseSwitch(button,image) {
		if(document.images) {
			document[button].src = '/images/' + image;
		}
	}