function show(field) {
    e = document.getElementById(field);
    if (e && e.style.visibility == 'hidden') {
	e.style.visibility = 'visible';
    } else if (e && e.timer) {
	clearTimeout(e.timer);
	e.timer = null;
    }
    hide(field, 10000);
    return true;
}
function real_hide(e) {
    e.style.visibility = 'hidden';
}
function hide(field, timeout) {
    e = document.getElementById(field);
    if (e && e.style.visibility == 'visible') {
	e.timer=setTimeout("real_hide(e)",timeout);
    }
    return true;
}