title: How to use setProgressDrawable() correctly?
body: <p>I am having problem with setting a new Drawable to my ProgressBar. </p>
  
  <p>If I use the setProgressDrawable() inside onCreate() method it works great. But when I try to call the same method inside a Handler post callback it doesn't work and the progressbar disapears.</p>
  
  <p>Can someone explain this behaviour? How can I solve this problem?</p>