title: Buttons interfere on overlapping fragments
body: <p>I have an app where one fragment is a "main menu" which can open a submenu (another fragment) based on which button is pressed.  Each submenu completely covers the main menu. When a button is pressed from the main menu, I add the transaction to the backstack like this so when the user hits the back button it will take him back to the main menu:</p>
  
  <pre><code>MyFragment frag = new MyFragment ();
  FragmentManager manager = getFragmentManager();
  FragmentTransaction transaction = manager.beginTransaction();
  transaction.add(R.id.main_layout, frag, "NextFrag");
  transaction.addToBackStack("NextFrag");
  transaction.commit();
  </code></pre>
  
  <p>I noticed that the buttons from my "main menu" fragment are still active from the second fragment even though you can't see them.  I came across <a href="https://stackoverflow.com/questions/15357721/android-fragments-overlap-previous-view-and-button-listeners">this post</a> which suggested making each fragments' layout clickable</p>
  
  <pre><code>android:clickable="true"
  </code></pre>
  
  <p>This works but I don't understand why and feel like I'm missing something.</p>