title: Why does the android jetpack NavigationUI navigateUp method only open the draw menu if you are at the start destination of the nav graph
body: <p>When using a <code>NavigationView</code> with a <code>DrawLayout</code> and an <code>ActionBar</code>, <code>jetpack</code> provides some powerful convenience methods to hook everything up together so that these items are easier to implement.</p>
  
  <p>The method <code>setupActionBarWithNavController</code> provided in the <code>NavigationUi</code> library is an extension method for activities that adds a hamburger button to open your drawer and if you override the <code>onSupportNavigateUp:Boolean</code> method on your activity to call <code>navigateUp(drawLayout:DrawLayout, navController:NavController)</code> method, that method will change the hamburger button to a back button and back automatically with a fancy animation, which is super cool.</p>
  
  <p>However it seems that this method is implemented as follows:</p>
  
  <pre><code> public static boolean navigateUp(@Nullable DrawerLayout drawerLayout,
          @NonNull NavController navController) {
      if (drawerLayout != null &amp;&amp; navController.getCurrentDestination().getId()
              == navController.getGraph().getStartDestination()) {
          drawerLayout.openDrawer(GravityCompat.START);
          return true;
      } else {
          return navController.navigateUp();
      }
  }
  </code></pre>
  
  <p>As you can see here, this method has the basic logic of:</p>
  
  <p><em>if you are not at the start destination of the navgraph, then the button is a back button, otherwise its a hamburger button</em></p>
  
  <p>This means that only the start destination can open the draw menu via an actionbar button, while all the other destinations have a back button instead, and must swipe to open the draw menu.</p>
  
  <p>Why is this the case? It seems this is a conscious design decision by the android team. Is it frowned upon to have a hamburger button available on multiple destinations?  </p>
  
  <p>I would like to have a few main branches that have a hamburger menu and all the screens that branch of from those to have a back button. Is there a way to implement multiple <code>NavGraphs</code> and link them together in one <code>NavigationView</code>?</p>
  
  <p>u_u</p>