title: VGroup: How to have a new element show up smoothly (resize) when added/removed
body: <p>When adding/removing elements to/from a VGroup I need it to happen smoothly, resize the item. I believe I have to use transition effects. But how?</p>
  
  <ol>
  <li>At item (element) level?</li>
  <li>At VGroup level?</li>
  <li>Should I use a DataGroup instead and do it at ItemRenderer level?</li>
  </ol>
  
  <p>I've been trying to do it at item level but I still didn't manage to make it work and somehow it doesn't feel right. It feels like it should be done at a higher level. </p>
  
  <p>For example, I defined a "death" state which resizes the item to height=0. But then, after it shrunk, it has to somehow notify VGroup in order for it to be removed or remove itself from VGroup. It feels unnecessarily complicated. </p>
  
  <p>What I am hoping for is a way to associate an effect to inserting and removing items from a VGroup? Any ideas?</p>
  
  <p>Thanks in advance,
  Nuno</p>