isIE=document.all;
    isNN=!document.all&&document.getElementById;
    isN4=document.layers;
 
function showfunction(div) {
      popup=isIE ? document.all.item(div) : document.getElementById(div);
      if (isIE||isNN) popup.style.visibility="visible";
      else if (isN4) document.popup.visibility="visible";
}

function hidefunction(div) {
      popup=isIE ? document.all.item(div) : document.getElementById(div);
      if (isIE||isNN) popup.style.visibility="hidden";
      else if (isN4) document.popup.visibility="hide";
}