window.onload = function() {
	if (document.getElementById("nav")) {
		var tags = document.getElementById("nav").getElementsByTagName("img");
		for (var i = 0; i <  tags.length  ; i++) {
			var tag = tags[i];
			if (tag.className != "current") {
				tag.onmouseover = function() {
					var thisId = this.id;
					//alert(thisId);
					document.getElementById(thisId).src = "img/" + thisId.replace("menu_", "") + "_on.jpg";
				}
				tag.onmouseout = function() {
					var thisId = this.id;
					//alert(thisId);
					document.getElementById(thisId).src = "img/" + thisId.replace("menu_", "") + ".jpg";
				}
			}
		}
	}
}