function fetch_object(idname)
{
	var my_obj = document.getElementById(idname);
	return my_obj;
}

function toggle_nav(obj)
{
	for (i = 1; i<= 8; i++  )
	{
		
		var nav_img = fetch_object("nav_" + i);
		var sub_nav = fetch_object("sub_nav_" + i);
		var sub_nav_index = fetch_object("sub_nav_0");
		sub_nav_index.style.display = "none";
		if (obj == i)
		{
			nav_img.src = "../images/menu/main_" + i + "a.jpg";
			sub_nav.style.display = "block";

		}
		else
		{
			nav_img.src = "../images/menu/main_" + i + ".jpg";
			sub_nav.style.display = "none";
		}
	}
}