document.submenus = new Array('Navigation1','Navigation2','Navigation3');

function display_menu(title){
	remove_menus();
	document.getElementById(title).style.visibility = 'visible';
	on_over();
}

function remove_menus(){
	for (i = 0; i < document.submenus.length; i++) {
		document.getElementById(document.submenus[i]).style.visibility = 'hidden';
	}
}

function on_out(){
	document.menutimer= window.setTimeout('remove_menus()', 1000);
}

function on_over(){
	window.clearTimeout(document.menutimer);
}

function on_over_clear(){
	remove_menus();
	on_over();
}