[Moo] Tween onComplete - for special fade.

[idan Hen]

Hey , 

i have a site i am building , i have a content div and in my header i have 
login button.
when i click the login button , i mask the content div , and display a 
float div above it.

so far its all good :) , i have a close button to close the floating div 
and unmask the content div.

the issue is : 
when i fade('out') , i want to unmask onComplete. -> the problem is this 
effect the fade('in') also !!

set("tween", {
            onComplete: function(o) {
                $('content').unmask();
            }
        }).

how can i set a "onComplete" to each fade ... -> they are both running on 
the same element .....