title: How to implement a bottom navigation drawer in Flutter
body: <p>I'm trying to implement a bottom navigation drawer, similar to the one used in the <a href="https://material.io/design/material-studies/reply.html#components" rel="noreferrer">Reply Material Study</a>, that is an extension of the bottom app bar, and opened and closed via an icon button in the bottom app bar.</p>
  
  <p><a href="https://i.stack.imgur.com/Py8Ey.png" rel="noreferrer"><img src="https://i.stack.imgur.com/Py8Ey.png" alt="Bottom Navigation Drawer for Reply"></a></p>
  
  <p>I've tried bottom sheets, but that replaces, or hovers on top of, the bottom app bar. I want it to look like the one in the screenshot where the bottom app bar stays on the screen and the bottom navigation drawer slides up when the "menu" button is tapped.</p>
  
  <p>The Material Design site shows this as a component, but doesn't link off to anywhere showing how to implement it in Flutter.</p>