title: How to be notified that a composite's child received/lost focus?
body: <p>I have an SWT <code>Composite</code> that I need to pass to some other code which will add children to it at will. Is there any way to be notified that a child of the composite received and lost focus?</p>
  
  <p>Just to make sure it's clear, I cannot add listeners to each child, because I'm not in charge of creating those controls. A child could be added at any time.</p>