window.onload = function() {
	
	var tags = document.getElementById("links").getElementsByTagName("img");
	for (var i = 0; i <  tags.length; i++) {
		var tag = tags[i];
		if (tag.className != "on") {
			tag.onmouseover = function() {
				//alert("ciao");
				thisId = this.id;
				thisIdR = thisId.replace("links_", "");
				document.getElementById(thisId).src = "img/" + thisIdR + "_on.jpg";
			}
			tag.onmouseout = function() {
				thisId = this.id;
				thisIdR = thisId.replace("links_", "");
				document.getElementById(thisId).src = "img/" + thisIdR + ".jpg";
			}
		}
	}
	
	var tags = document.getElementById("menuLinks").getElementsByTagName("a");
	for (var i = 0; i <  tags.length; i++) {
		var tag = tags[i];
		if (tag.className != "on") {
			tag.onmouseover = function() {
				thisId = this.id;
				//alert(thisId);
				thisIdR = thisId.replace("menu_", "btn_");
				//alert(document.getElementById(thisId).style.backgroundImage);
				document.getElementById(thisId).style.backgroundImage = "url(img/" + thisIdR + "_on.jpg)";
			}
			tag.onmouseout = function() {
				thisId = this.id;
				thisIdR = thisId.replace("menu_", "btn_");
				document.getElementById(thisId).style.backgroundImage = "url(img/" + thisIdR + ".jpg)";
			}
		}
	}

}