title: Set height of DropdownButtonFormField list
body: <p>In Flutter, <code>DropdownButtonFormField</code>'s modal list keeps growing to fill some height limit that seems to be ~90% of the screen (or possibly, and more likely, the <code>Container</code> it's in). When it reaches that limit, it becomes scrollable. Is it possible to set that height limit?</p>
  
  <p>Here's the code I'm working with</p>
  
  <pre><code>Scaffold(
    appBar: AppBar(title: Text(widget.title)),
    body: Container(
        padding: EdgeInsets.fromLTRB(5, 5, 5, 5),
        child: Form(
          child: ListView(
            scrollDirection: Axis.vertical,
            children: &lt;Widget&gt;[
              //other widgets here
              DropdownButtonFormField(items: this.dropDownItems),
            ],
          ),
        )),
  );
  </code></pre>