IE4 = (document.all) ? 1 : 0;
NS4 = (document.layers) ? 1 : 0;
DOM = (document.getElementById) ? 1 : 0;
verOK = (IE4 || NS4 || DOM) ? 1 : 0;

function submenuOver(on) {
    if (!verOK) { return }
    // the div element id is "button"
    if (DOM) { whichEl = document.getElementById("button").style; }
        else if (IE4) { whichEl = document.all.button.style }
        else { whichEl = document.button.document.button };

    if (!on) { whichEl.visibility = "hidden"; return }
        else {whichEl.visibility = "visible"}
}