title: Flutter listview button to create extra children
body: <p>I have a listview in a flutter application I am working on, and I want to be able to add extra items to the listview based on when a button is pressed.  The button should be below all of the items.  I want to add an extra container every time a button is pressed.  Ideally, it would be a widget.  I am not sure how to do this.  Here is my code:</p>
  
  <pre><code>body: ListView(
            children: &lt;Widget&gt;[
              Container(   //this is the container I would like to add another of when a button is pressed
                height: 200,
                child: optionsChoices(),
              ), //end container
              Container(
                height: 200,
                child: optionsChoices(),
              ),
              Container(
                height: 200,
                child: optionsChoices(),
              ),
              Container(
                height: 200,
                child: optionsChoices(),
              ),
            ]
          )
  
  </code></pre>
  
  <p>Thanks!</p>