function rollover(id) {
	var el = document.getElementById(id);
	if (el) {
		var imgs = el.getElementsByTagName('img');
		for (var i = 0; i < imgs.length; i++) {
			var src = imgs[i].src;
			if (src.indexOf('-off.') != -1) {
			  imgs[i].srcOld = src;
			  imgs[i].srcNew = src.replace('-off.', '-on.');
			  var img = new Image(1,1);
	          img.src = imgs[i].srcNew;
			  
			  imgs[i].onmouseover = function(){this.src = this.srcNew;};
			  imgs[i].onmouseout = function(){this.src = this.srcOld;};
			}
		}
	}
}