title: ExtJs4 how to disable all fields and all buttons on a panel recursively
body: <p>I'm trying to disable all clickable, editable components on my panel.</p>
  
  <p>Calling <code>panel.disable()</code> grays it out, but buttons are still clickable.
  The same result gives <code>panel.cascade</code> with a function that disables each component. </p>
  
  <p>What is the right way to do this?</p>