title: Android viewGroup listen to child view visibility changes
body: <p>I have an android custom <code>ViewGroup</code></p>
  
  <p>I need to receive children <code>visibility</code> changes and then make some change to my logic and ...</p>
  
  <p>for example: I set <code>view1</code> in a <code>RelativeLayout</code> above <code>view2</code> and when <code>view2</code> set it's <code>visibility</code> to <code>GONE</code> I must change <code>view1</code> design roles and ...</p>