function initSubMenu () {
	if (_('nav')) {
		var menu_items = _('nav').getElementsByTagName('li');
		
		for (var i = 0; i < menu_items.length; i++) { 
		    if (menu_items[i].id.substr(0,3)== "nav") { 
		    	menu_items[i].onmouseover = function() {
		    		var sub = this.getElementsByTagName('ul');
		    		css('add',sub[0],'hover');
				}
				menu_items[i].onmouseout = function() {
		    		var sub = this.getElementsByTagName('ul');
						css('remove',sub[0],'hover');
				}
		    }
		}
	}
}

function init() {
	/* init submenu for internet explorer */
	if (isIE) {
		initSubMenu();
	}
}

function addLoadEvent(func) {
    var oldonload = window.onload;
    if (typeof window.onload != 'function') {
        window.onload = func;
    } else {
        window.onload = function() {
            if (oldonload) {
                oldonload();
            }
            func();
        }
    }
}

addLoadEvent(init);