var ie = (document.all)?1:0; // IE4
var ns4 = (document.layers)?1:0; // Netscape 4
var ie5 =(document.getElementById)?1:0; // DOM3 = IE5+, NS6
function hide_show() {
if (ns4) {
  if (document.myLayer.visibility == 'show')
  document.myLayer.visibility = 'hide';
  else
  document.myLayer.visibility = 'show';
  }
else if (ie) {
if (document.all.myLayer.style.visibility == 'visible')
    document.all.myLayer.style.visibility = 'hidden';
    else
    document.all.myLayer.style.visibility = 'visible';
    }
else if (ie5) {
  if (document.getElementById('myLayer').style.visibility == 'visible')
  document.getElementById('myLayer').style.visibility = 'hidden';
  else
  document.getElementById('myLayer').style.visibility = 'visible';
  }
}