title: How to do Navigator.popUntil properly when using different animations for each push
body: <p>I am trying to rebuild iOS app in Flutter, but facing a problem with navigation.</p>
  <p>Here what I am trying to do:</p>
  <ol>
  <li>List of Added Exchange Pairs with Add button (A screen)</li>
  <li>Add button opens Picker with Exchanges (B screen) with transition from bottom to top.</li>
  <li>By tapping on exchange it pushes new Picker with Pairs (C
  screen) with transition from right to left.</li>
  <li>when user taps on pair it closes all pickers at once and deliver result of picking to A screen.</li>
  </ol>
  <p>I have tried double pop and popUntil but result always same, I see 2 back transitions (left to right and top to bottom) at same time.</p>
  <h2>How it looks in iOS native app:</h2>
  <p><a href="https://i.stack.imgur.com/nZhgi.gif" rel="noreferrer"><img src="https://i.stack.imgur.com/nZhgi.gif" alt="How it looks in iOS native app" /></a></p>
  <h2>How it looks in Flutter app:</h2>
  <p><a href="https://i.stack.imgur.com/0SRbH.gif" rel="noreferrer"><img src="https://i.stack.imgur.com/0SRbH.gif" alt="How it looks in Flutter app" /></a></p>
  <h2>Solved with nested Navigator</h2>
  <p>Wrapped Screen B with Navigator and used this navigator to push screen C, on screen C used root navigator to pop. Result is below:
  <a href="https://i.stack.imgur.com/96nRv.gif" rel="noreferrer"><img src="https://i.stack.imgur.com/96nRv.gif" alt="Final result" /></a></p>