title: Make Container size as parent Stack size
body: <p>I need draw the widget over some other content by condition. I want to align this widget as I want (using <code>Alignment</code>). I supposed that I need to use a <code>Stack</code>, i.e.</p>
  
  <pre class="lang-dart prettyprint-override"><code>Stack(
    children: [
      Column(), // Content
      Visibility(
        visible: isVisible, // condition is here
        child: Container(
          //height: double.infinity, // cause rendering crash
          child: Container(
            padding: ...,
            margin: ...,
            color: Colors.red,
            child: Text('message')
          ),
        ),
      ),
    ],
  )
  </code></pre>
  
  <p>I need that first <code>Container</code> will populate the whole place which <code>Stack</code> and place the second <code>Container</code> in any place inside first <code>Container</code>. </p>
  
  <p>The desired initial condition do not use <code>Positioned</code>.</p>
  
  <p>So is it possible in principle? If no, <code>Positioned</code> can be used. I am implement a-like <code>SnackBar</code> rectangle which I can place inside parent rectangle.</p>