function goInitMenu() {
	if(menu = document.getElementById('main_menu')) {
		var links = menu.getElementsByTagName('a');
		for(var i = 0; i < links.length; i++) {
			var a = links[i];
			UbiEvent.addEvent(a, 'mouseover', goHandleRollover, false);
			UbiEvent.addEvent(a, 'mouseout', goHandleRolloverExit, false);
		}
	}
}

function goHandleRollover(e) {
	var t = UbiEvent.getTarget(UbiEvent.getEvent(e));
	while(t != document.body && t.nodeName.toLowerCase() != 'li') t = t.parentNode;
	t.style.backgroundImage = "url(img/button_back_left_over.jpg)";
}

function goHandleRolloverExit(e) {
	var t = UbiEvent.getTarget(UbiEvent.getEvent(e));
	while(t != document.body && t.nodeName.toLowerCase() != 'li') t = t.parentNode;
	t.style.backgroundImage = "url(img/button_back_left.jpg)";
}

UbiEvent.addEvent(window, 'load', goInitMenu, false);