title: Adding icon to left of DropDownButton (expanded) in flutter
body: <p>I want to add icon to left of <code>DropDownButton</code> but can't find a way to do so.
  What I want to achieve is like this:</p>
  
  <p><a href="https://i.stack.imgur.com/wNoZ5.png" rel="noreferrer"><img src="https://i.stack.imgur.com/wNoZ5.png" alt="enter image description here"></a></p>
  
  <p>I have tried following code but it places icon to right where I don't want it and it also overrides arrow icon:</p>
  
  <pre><code> `@override
    Widget build(BuildContext context) {
    return Scaffold(
    body: Container(
      margin: EdgeInsets.only(top: 64.0, left: 16.0, right: 16.0),
      color: Colors.white,
      child: DropdownButton(
        icon: Icon(
          Icons.person,
          color: Colors.redAccent,
          size: 20.09,
        ),
        isExpanded: true,
        items: _studentList.map((val) {
          return DropdownMenuItem(
            value: val,
            child: Text(val),
          );
        }).toList(),
        value: _currentSelectedItem,
        onChanged: (value) {
          setState(() {
            _currentSelectedItem = value;
          });
        },
      ),
    ),
  );
    }`
  </code></pre>
  
  <p>Output of above code is like this:</p>
  
  <p><a href="https://i.stack.imgur.com/r7tAW.png" rel="noreferrer"><img src="https://i.stack.imgur.com/r7tAW.png" alt="enter image description here"></a></p>
  
  <p>I have also tried to place <code>Icon()</code> and <code>DropDownButton()</code> inside <code>Row()</code> widget but that does not allow the <code>DropDownButton()</code> to expand to full width.</p>
  
  <p>Any help would be appreciated.</p>
  
  <p>Thanks</p>