title: Replace only children when calling Navigator.of(context).push()
body: <p>I am creating a Picture in Picture Widget and I render two screens, one that is floating and the other that stays in the background (both are Scaffolds). When I use <code>Navigator.of(context).push()</code> I would like to have replaced only the background view. The current behavior I get, is a screen is pushed over both screens. Is there any way to create a subnavigator? I was thinking about something that could be used like this:</p>
  
  <pre><code>Navigator(
    child: MyWidget(),
  )
  </code></pre>
  
  <p>And after doing this when I called <code>Navigator.of(context)</code> this navigator would be returned and this navigator would only replace children widgets.</p>
  
  <p>For better understanding of what I am talking about I made a video about the current behavior I am getting:</p>
  
  <p><a href="https://youtu.be/L4V4bcZAppI" rel="nofollow noreferrer">https://youtu.be/L4V4bcZAppI</a></p>