function tab_menu2()
{

document.getElementById("n4tab1_Content1").style.display = "block";
document.getElementById("n4tab1_Content2").style.display = "none";
}
function tab_menu3()
{

document.getElementById("n4tab1_Content1").style.display = "none";
document.getElementById("n4tab1_Content2").style.display = "block";
}