title: Flutter: disable sliverAppBar padding animation
body: <p>I want to attach custom menu bar (full width) to the <code>sliverAppBar</code> widget so that it will stick to the bottom of sliverAppBar background and will be always visible.</p>
  
  <p>To solve this I've put <code>Row</code> widget into <code>FlexibleSpaceBar.title</code> parameter but now I have one unexpected problem.</p>
  
  <p>When I wrap anything inside <code>FlexibleSpaceBar.title</code> parameter into a <code>Row</code> widget it starts to animate overflowed padding. Also it expands <code>Row</code> widget outside screen bounds. That was unexpected behavior.</p>
  
  <p>I don't want to shrink title padding or resize title on SliverList scroll.</p>
  
  <p><a href="https://i.stack.imgur.com/pZVAP.gif" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/pZVAP.gif" alt="You can&#39;t watch [screencast here][1]"></a></p>
  
  <pre><code>SliverAppBar(
    expandedHeight: 200.0,
    floating: false,
    pinned: true,
    elevation: 0.0,
    flexibleSpace: SafeArea(child: // &lt;-- SafeArea doesn't work for FlexibleSpaceBar.title in this case
      FlexibleSpaceBar(
        background: Row(
          mainAxisAlignment: MainAxisAlignment.center,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Image.asset(
              'assets/images/store.png',
              fit: BoxFit.cover,
              width: 120,
              height: 120,
            ),
          ],
        ),
        collapseMode: CollapseMode.none,
        titlePadding: EdgeInsetsDirectional.only(start: 100, bottom: 0), // &lt;-- have to add 100 to padding to keep in safe area on the screen
        title: Row( // &lt;-- animation enables by default if wrapped in a Row widget
          children: [
            Icon(Icons.menu, size: 40, color: Colors.white,),
          ]
        )
      )
    )
  ),
  </code></pre>
  
  <p>How to disable this shrink, size and animation in sliverAppBar for FlexibleSpaceBar title?</p>