title: How to remove extra padding around AppBar leading icon in Flutter
body: <p>In my Flutter app, I have this AppBar</p>
  
  <pre><code>Widget setAppBar(){
    return new AppBar(
      title: addAppBarTextWidget('Explore'),
      elevation: 0.0,
      leading: addLeadingIcon(),
      actions: &lt;Widget&gt;[
        addAppBarActionWidget(Constant.iconNotification, 22.0, 16.0, 8.0),
        addAppBarActionWidget(Constant.iconProfile, 30.0, 30.0, 15.0)
      ],
    );
  }
  
  Widget addLeadingIcon(){
    return new Container(
      height: 25.0,
      width: 25.0,
      padding: const EdgeInsets.fromLTRB(0.0, 0.0, 0.0, 0.0),
      margin: const EdgeInsets.fromLTRB(0.0, 0.0, 0.0, 0.0),
      child: new Stack(
        alignment: AlignmentDirectional.center,
        children: &lt;Widget&gt;[
          new Image.asset(
            Constant.iconNotification,
            width: 25.0,
            height: 25.0,
          ),
          new FlatButton(
              onPressed: (){
                onLeadingShowCategoryClick();
              }
          )
        ],
      ),
    );
  }
  </code></pre>
  
  <p><strong>it looks like:</strong></p>
  
  <p><a href="https://i.stack.imgur.com/JuaYC.png" rel="noreferrer"><img src="https://i.stack.imgur.com/JuaYC.png" alt="enter image description here"></a></p>
  
  <blockquote>
    <p>As you can see on the AppBar, there is some extra padding around the
    leading icon. How can I remove this extra padding.</p>
  </blockquote>