title: How to display snackbar infinite duration in flutter?
body: <p>I created flutter project in android studio and tried to show snackbar infinite duration.This is my code</p>
  
  <pre><code> final snackBar = SnackBar(
      content: Text('Cart:'+countProducts.toString()+" Products($countCost:sum)",style: TextStyle(color: Colors.black),),
        shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.only(topLeft:Radius.circular(22),topRight:Radius.circular(22))),
      backgroundColor: Colors.white70,
      action: SnackBarAction(
        textColor: Colors.blueAccent,
        label: "Buy",
        onPressed: () {
          // Some code to undo the change.
        },
      ),
    );
  
    Scaffold.of(context).showSnackBar(snackBar);
  </code></pre>
  
  <p>There is another button that will change snackbar text. But I do not want to it dismiss back.So how to display snackbar infinite duration in flutter</p>