function toggle_visibility(id) {
    var e = document.getElementById(id);
    if (e.style.display == 'block')
        e.style.display = 'none';
    else
        e.style.display = 'block';
}

function doa(e) {
    var na = navigator.appName;
    var m = 'For more information, see below';

    if (na == 'Netscape' && e.which == 3) {
        alert(m);
        return false;
    }
    if (na == 'Microsoft Internet Explorer' && event.button == 2) {
        alert(m);
        return false;
    }
    else {
        return true;
    }
}

function tr() {
    document.onmousedown = doa;
    document.onmouseup = doa;
}