[Moo] Need help with code move from 1.1 to 1.2

[Philip]

Hey there...

I have some code that was working great in MooTools 1.1. I upgraded to
1.2 in order to use some new tools which ended up breaking one. I was
hoping someone could help me update this code to work with MooTools
1.2. The biggest change is obviously changing Fx.Style to Fx.Tween
which when done, creates an error Fx.Durations is null or not an
object. If someone can give me a hand, it would be much appreciated.
Thanks.

window.addEvent("domready",function(){
        var $b = $(document.getElementsByTagName('body')[0]);

        // animation classes - Fx.Height and Fx.Opacity
        Fx.Opacity = Fx.Style.extend({initialize: function(el, options)
{this.now = 1;this.parent(el, 'opacity', options);},toggle: function()
{return (this.now > 0) ? this.start(1, 0) : this.start(0, 1);},show:
function(){return this.set(1);}});

        // help vars
        if($('popup_login')) var popup_login = new Fx.Opacity('popup_login',
{duration: 250}).set(0);
        if($('popup_login')){
                $('popup_login').setStyle("display", "block");
                $('close_button_login').addEvent("click", function()
{popup_login.start(0);});
        }
        if($('popup_register')) var popup_register = new Fx.Opacity
('popup_register', {duration: 250}).set(0);
        if($('popup_register')){
                $('popup_register').setStyle("display", "block");
                $('close_button_register').addEvent("click", function()
{popup_register.start(0);});
        }
        // login
        if($('login_btn')) $('login_btn').addEvent("click", function(e){new
Event(e).stop();popup_login.start(1);});
        if($('login_btn_noborder')) $('login_btn_noborder').addEvent("click",
function(e){new Event(e).stop();popup_login.start(1);});
        // register
        if($('register_btn')) $('register_btn').addEvent("click", function(e)
{new Event(e).stop();popup_register.start(1);});
        if($('register_btn_noborder')) $('register_btn_noborder').addEvent
("click", function(e){new Event(e).stop();popup_register.start(1);});
});