title: Navigation Component, Control when to show hamburger or back icon
body: <p>I have the following Activity</p>
  
  <pre><code>class MainActivity : AppCompatActivity() {
  
  private lateinit var drawerLayout: androidx.drawerlayout.widget.DrawerLayout
  
  override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.main_activity)
  
      drawerLayout = drawer_layout
  
      val navController = Navigation.findNavController(this, R.id.fragment_main_navHost)
  
      setSupportActionBar(toolbar)
  
      NavigationUI.setupActionBarWithNavController(this, navController, drawerLayout)
      navView_main.setupWithNavController(navController)
  }
  
  override fun onSupportNavigateUp(): Boolean {
      return NavigationUI.navigateUp(drawerLayout,
          Navigation.findNavController(this, R.id.fragment_main_navHost))
  }
  
  override fun onBackPressed() {
      if (drawerLayout.isDrawerOpen(GravityCompat.START)) {
          drawerLayout.closeDrawer(GravityCompat.START)
      } else {
          super.onBackPressed()
      }
  }
  </code></pre>
  
  <p>which as you can see is associated with navigation graph, and I am using a navigation drawer. When I am navigating through the items in the drawer I want to keep the hamburger icon, and only change it to up/back button when I click on an item within the fragment or popup for example and ensure that the behavior of the system reflects what the user expects based on the icon displayed. Is that possible </p>