title: How to position a Column inside the stack based on the fractional height of screen in flutter?
body: <p>I want to position the <code>Column</code> inside the <code>Stack</code>, so that it takes 60% of the screen, and that it is positioned at the bottom of the screen. </p>
  
  <pre><code>////////
  |
  |
  |40%
  ////////
  |column
  |
  |
  |
  |60%
  ////////
  </code></pre>
  
  <p>Currently I am trying to do it with <code>Positioned</code> and with <code>MediaQuery</code> But It doesnt work.</p>
  
  <pre><code>      new Positioned(
          top: MediaQuery.of(context).size.height * .4,
          height: MediaQuery.of(context).size.height * .6,
  
          child: new Column(
  </code></pre>
  
  <p>I know there are some Fractional Widgets that should help. </p>