var ns4 = document.layers;
var ie4 = document.all;
var nn6 = document.getElementById && !document.all;


function hidewindow(div_id) 
{
  if (ns4) {
     document.login.visibility = "hide";
  }
  else if (ie4) {
     document.all['login'].style.visibility = "hidden";
  }
  else if (nn6) {
     document.getElementById('login').style.visibility = "hidden";
  }
}

function showwindow() {
  if (ns4) {
     document.login.visibility = "show";
  }
  else if (ie4) {
     document.all['login'].style.visibility = "visible";
  }
  else if (nn6) {
     document.getElementById('login').style.visibility = "visible";
  }
}