function twitterToggle() {
    var r = document.getElementById('twitter-reg');
    var u = document.getElementById('twitter-unreg');
    if(r.style.display == 'block') {
        r.style.display = 'none'; 
        u.style.display = 'block';
    } else {
        r.style.display = 'block'; 
        u.style.display = 'none';
    }
    return true;
}