NS4 = (document.layers);
	IE4 = (document.all);
	ver4 = (NS4 || IE4);
	IE5 = (IE4 && navigator.appVersion.indexOf("5.")!=-1);
	isMac = (navigator.appVersion.indexOf("Mac") != -1);
	isMenu = (NS4 || (IE4 && !isMac) || (IE5 && isMac));
	
	if (!ver4) event = null;