title: Flutter - custom alert dialog not showing
body: <p>I am building a <code>custom alert dialog</code> using flutter/Dart and a <a href="https://gist.github.com/bostrot/1f142e37a4863b724ba7afea3abe98b9" rel="noreferrer">Custom Show Dialog</a> class that I got from Github and for a reason or another the dialog is not showing.</p>
  
  <p><strong>Q:</strong> How to get the dialog to show properly?</p>
  
  <p><strong>PS</strong> <code>resultsDialog(a,b)</code> is being called on a button click elsewhere. </p>
  
  <p>Here's my code for the Alert dialog:</p>
  
  <pre><code>Future&lt;void&gt; resultsDialog(String sq, String sl) async {
    BuildContext ctx;
    CustomAlertDialog dialog = new CustomAlertDialog(
      content: Material(
        type: MaterialType.card,
        child: new Container(
          margin: EdgeInsets.only(left: 26.0, right: 26.0),
          decoration: new BoxDecoration(
          shape: BoxShape.rectangle,
          color: const Color(0xFFFFFF),
          borderRadius:
            new BorderRadius.all(new Radius.circular(32.0)),
          ),
          child: new Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: &lt;Widget&gt;[
              // dialog top
              new Expanded(
                  //...
              ),
              // dialog center row
              new Expanded(
                  //...
              ),
              // dialog bottom row
              new Expanded(
                  //...
              ),
            ],
          ),
        ),
      ),
    );
    customShowDialog(context: ctx, child: dialog);
  }
  </code></pre>
  
  <p>Expected result:</p>
  
  <p><a href="https://i.stack.imgur.com/UoEcT.png" rel="noreferrer"><img src="https://i.stack.imgur.com/UoEcT.png" alt="enter image description here"></a></p>
  
  <p><strong>PS</strong> I got the inner rows takes care of so the problem here is only getting the dialog to show up and prevent it from being dismissed that's all</p>