title: Usage of android.support.v4.app or android.app for DialogFragment?
body: <p>Reading through official documentation of Android made me little bit confused about this 2 libraries. When should I use one and when the other one?</p>
  
  <p>As far as I'm understanding, it's the best to use Android Support library depending to the number of devices that will be able to run it and the look will stay always the same. No matter what might get in the future of the android, Support library will always be supported on any future Android API. But why is then DialogFragment for android.app? It is logic to me that android.app.DialogFragment has some benefits which that from support's doesn't because anyways it would be useless to have it, since it's not supported on so many devices. </p>
  
  <p>Can you help me which I should prefer to use it and if my sayings were right?</p>