// this script enables rollover images. two requirements:
// 1. each image must have a class name of "rollover"
// 2. each image must have a unique id
// e.g. <img src="/images/topnav_about.jpg" id="t_about" class="rollover" />

var rollovers = new Array();

function initRollovers() {
	if ( document.getElementsByTagName && document.getElementById ) {
		imgs = document.getElementsByTagName('img');
		for ( i = 0; i < imgs.length; i++ ) {
			var img = imgs[i];
			if (img.className == 'rollover') {
				var rolloverId = img.id + '_over';
				rollovers[img.id] = new Image();
				rollovers[img.id].src = img.src;
				rollovers[rolloverId] = new Image();
				rollovers[rolloverId].src = img.src.replace(".jpg", "_over.jpg");
				rollovers[rolloverId].src = img.src.replace(".gif", "_over.gif");

				img.onmouseover = function() {
					var rolloverId = this.id + "_over";
					this.src = rollovers[rolloverId].src;
				}
				img.onmouseout = function() {
					this.src = rollovers[this.id].src;
				}
			}
		}
	}
}

addLoadEvent( initRollovers );