title: How does WhatsApp pop-up notification work?
body: <p>I am trying to mimic the pop-up notification of WhatsApp.
  (If you have not seen it, it might be a bit hard for you to understand this.)
  Below is an image to give a clearer perspective.</p>
  
  <p><img src="https://i.stack.imgur.com/jKI1f.jpg" alt="whatsapp pop up notificaiton"></p>
  
  <p>Some suggested that this might be done using an oridnary activity which has the <code>Theme.Holo.Light.Dialog.Alert</code> theme. However, when I implemented that I got half of the activity full with the views (and the other half) which is supposed to be empty like a dialog, showing a white background. ie, I did not have the dialog feel.</p>
  
  <p>Morever, when the device is in standby mode (power button pressed) and locked, whatsapp is able to bypass that and show the popup dialog (or activity, or whatever) above that.</p>
  
  <p>Any ideas how to implement this ?</p>