function menu_mouseover(id) {
	var img = document.getElementById("menu_" + id);
	if (img != null)
		img.src = "images/header-" + id + "_on.gif";
}

function menu_mouseout(id) {
	var img = document.getElementById("menu_" + id);
	if (img != null)
		img.src = "images/header-" + id + (id == currentPage ? "_on" : "") + ".gif";
}