var W3CDOM = (document.createElement && document.getElementsByTagName);

function initMenu() {
	if (!W3CDOM) return;
	menu = document.getElementById('topmenu');
	imgs = menu.getElementsByTagName('img');
	for (var i=0; i<imgs.length; i++) {
		if (imgs[i].className.indexOf('menu_') == -1) return;
		createMouseOver(imgs[i]);
	}
}

function createMouseOverById(id) {
	if (document.getElementById) createMouseOver(document.getElementById(id));
}

function createMouseOver(img) {
	if (!img) return;
	var pos = img.src.lastIndexOf('.');
	img.origSrc = img.src;
	img.overSrc = img.src.substring(0,pos) + '_over' + img.src.substring(pos);
	img.onmouseover = mouseOver;
	img.onmouseout = mouseOut;
	preload = new Image();
	preload.src = img.overSrc;
}
function mouseOver() {
	this.src = this.overSrc;
}
function mouseOut() {
	this.src = this.origSrc;
}