title: Blur or dim background when Android PopupWindow active
body: <p>I would like to be able to either blur or dim the background when I show my popup window using <code>popup.showAtLocation</code>, and unblur/dim the background when <code>popup.dismiss</code> is called.</p>
  
  <p>I have tried applying layout params <code>FLAG_BLUR_BEHIND</code> and <code>FLAG_DIM_BEHIND</code> to my activity, but this appears to just blur and dim the background as soon my app is started.</p>
  
  <p>How can I do blurring/dimming just with popups?</p>