title: Android Up Navigation Doesn't Work
body: <p>I'm trying to implement navigation according to: <a href="http://developer.android.com/training/implementing-navigation/ancestral.html">http://developer.android.com/training/implementing-navigation/ancestral.html</a></p>
  
  <pre><code>@Override
  public boolean onOptionsItemSelected(MenuItem item) {
      switch (item.getItemId()) {
      // Respond to the action bar's Up/Home button
      case android.R.id.home:
          Intent upIntent = NavUtils.getParentActivityIntent(this);
          if (NavUtils.shouldUpRecreateTask(this, upIntent)) {
              // This activity is NOT part of this app's task, so create a new task
              // when navigating up, with a synthesized back stack.
              TaskStackBuilder.create(this)
                      // Add all of this activity's parents to the back stack
                      .addNextIntentWithParentStack(upIntent)
                      // Navigate up to the closest parent
                      .startActivities();
          } else {
              // This activity is part of this app's task, so simply
              // navigate up to the logical parent activity.
              NavUtils.navigateUpTo(this, upIntent);
          }
          return true;
      }
      return super.onOptionsItemSelected(item);
  }
  </code></pre>
  
  <p>but <code>if (NavUtils.shouldUpRecreateTask(this, upIntent)) {</code> is returning FALSE always.</p>
  
  <p><strong>How is this code useful? In which cases it does return true?</strong></p>