var dom = (document.getElementById && !document.all) ? 1 : 0;
var open1 = "";

function show_hide(id) {
    var ob = (dom) ? document.getElementById(id) : document.all[id];

    if (ob.style.visibility == "hidden") {
        if (open1 != "") {
            open1.style.visibility = "hidden";
            open1.style.display = "none";
        }
        else {
            var menu1 = (dom) ? document.getElementById('menu1') : document.all['menu1'];
            menu1.style.visibility = "hidden";
            menu1.style.display = "none";
        }
        ob.style.visibility = "visible";
        ob.style.display = "block";
        open1 = ob;
    }
}