title: how to animate collapse elements in flutter
body: <p>How can i expand and collapse widget when user taps on different widget ( sibling or parent ) with animation ? </p>
  
  <pre><code>new Column(
      children: &lt;Widget&gt;[
          new header.IngridientHeader(
              new Icon(
                  Icons.fiber_manual_record,
                  color: AppColors.primaryColor
              ),
              'Voice Track 1'
          ),
          new Grid()
      ],
  )
  </code></pre>
  
  <p>I want user to be able to tap on header.IngridientHeader and then Grid widget should toggle ( hide if visible and other way around )</p>
  
  <p>edit:</p>
  
  <p>im trying to do something that in bootstrap is called Collapse. <a href="http://getbootstrap.com/docs/4.0/components/collapse" rel="noreferrer">getbootstrap.com/docs/4.0/components/collapse</a> </p>
  
  <p>edit 2:
  header.IngridientHeader should stay in place all the time
  Grid() is scrollable ( horizontal ) widget.</p>