title: add View by using WindowManager, but can back key press
body: <p>I've add a View, by using WindowManager.</p>
  
  <p>It shows properly what I wanted to do,</p>
  
  <p>but I have a problem.
  this is the problem.</p>
  
  <ul>
  <li>back key press doesn't affect under android component(like activity)</li>
  </ul>
  
  <p>what I want is my added view can focusable, ( can click the view's inner button ) 
  only when click the view,
  and outside of the view can process their work. 
  ( for example, if there is a button, can be clicked, and when back key press, top activity was gone )</p>
  
  <p>but if I add a flag - WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
  then I can't receive onClick method on my added view's button.
  but back button work correctly.</p>
  
  <p>otherwise, if i remove the flag -I can receive onClick callback, 
  but now back button doesn't work.</p>
  
  <p>I have a dilema. :(</p>
  
  <p>Thank you.</p>