// Unobtrusive image roll-over script from JavaScript_the_Definitive_Guide 5th Ed. O'Reilly
// page 533 (see source for comments)
//
function addRollover(img, rolloverURL) {
	if (typeof img == "string") {
		var id = img;
		img = null;
		
		if (document.getElementByID) img = document.getElementById(id);
		else if (document.all) img = document.images[id];
		
		if (!img) return;
		}
	if (img.tagName.toLowerCase() != "img") return;
	
	var baseURL = img.src;
	
	(new Image()).src = rolloverURL;
	
	img.onmouseover = function () { img.src = rolloverURL; }
	img.onmouseout = function () { img.src = baseURL; }
}
function initRollovers() {
	var images = document.getElementsByTagName("img");
	for (var i = 0; i < images.length; i++) {
		var image = images[i];
		var rolloverURL = image.getAttribute("rollover");
		if (rolloverURL) addRollover(image, rolloverURL);
	}
}
if (window.addEventListener)
	window.addEventListener("load", initRollovers, false);
else if (window.attachEvent)
	window.attachEvent ("onload", initRollovers);