title: MooTools: Fade out element?
body: <p>I have an Element object that I'm currently calling .hide() on. Instead, I'd like to fade out the opacity of the entire Element (and its children) to 100% (hidden) as a transition effect over maybe 500 ms or 1000 ms.</p>
  
  <p>Can Fx.Tween be used for this? Is this possible--does the MooTools framework have an effect like this in its UI library?</p>