title: Flutter：How to create a full screen mask view
body: <p>Now I'm using the showModalBottomSheet,</p>
  
  <p>when I click on the semi-transparent bottomsheet, it pops this view out, but what I want is that it doesn't respond to the user's click and still stays there, how do I do that?</p>
  
  <p>How to create a full screen mask view?</p>
  
  <p><a href="https://i.stack.imgur.com/uSYr3.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/uSYr3.png" alt="enter image description here"></a></p>