title: Snackbar duration and height
body: <p>I'm trying to show a snackbar.<br>
  After I click on a gesture detector, this snack has two buttons.<br>
  The problem is that the snackbar appears for seconds and then disappears.  </p>
  
  <p>So I have two questions:</p>
  
  <ol>
  <li>How to stop the snackbar from disappearing until the user takes an action and clicks on a button? </li>
  <li>Also, the snackbar has a height of the whole screen.<br>
  How can I make it have a specific height in the bottom of the screen?</li>
  </ol>