title: What event is triggered when a tab fragment is selected
body: <p>I'm using tab fragments in an activity and the actionbar hosts the tabs. 
  What I want to do is that whenever a fragment appears (or re-appears) in the view (selected by the user), I start doing something. I cannot use <code>onResume</code> of the fragment in this case, since all tabs are never really 'paused' when the user selects another tab, so <code>onResume</code> is not called</p>
  
  <p>I can use the two following events from the hosting activity, but I don't want them since I expect the fragment should know this logic on its own and do that task. Any idea? tks.</p>
  
  <pre><code>  @Override
      public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
          // When the given tab is selected, switch to the corresponding page in the ViewPager.
          mViewPager.setCurrentItem(tab.getPosition());
      }
  
      @Override
      public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
      }
  </code></pre>