title: Flutter. Using Theme, how to change scroll offset color?
body: <p>For beginning I am very sorry for my English. I am not a native speaker and additionally this is my first post in this language. I will be grateful for your understanding. 
  Here is what I mean:</p>
  
  <p><img src="https://i.stack.imgur.com/2U2HB.jpg" alt="my screenshot"></p>
  
  <p>How to set scroll color other than this green in dark theme? I can't do this. </p>
  
  <p>Below is my code:</p>
  
  <pre><code> theme: ThemeData(
      brightness: Brightness.dark,
      primaryColor: Colors.pink,
      backgroundColor: Colors.grey[900],
      textSelectionColor: Colors.pink,
      textSelectionHandleColor: Colors.pink[700],  
  
      textTheme: TextTheme(
        body1: TextStyle(color: Colors.white),
      ),
  
    ),
  </code></pre>
  
  <p>Thank you in advance for your help :)</p>