title: Subtitle in AppBar
body: <p>I have a SliverAppBar with title and subtitle like this:</p>
  
  <pre><code>SliverAppBar(
                    backgroundColor: Colors.white,
                    forceElevated: true,
                    elevation: 1.0,
                    pinned: true,
                    floating: true,
                    snap: false,
                    title: Column(
                      children: &lt;Widget&gt;[
                      Container(padding: EdgeInsets.only(top: 6.0, bottom: 5.0),
                        child: Text('Contest', style: TextStyle(color: Colors.black, fontWeight: FontWeight.w500))),
                      Text(_getFiltersString(), style: TextStyle(fontSize: 14.0, color: Colors.grey[700]),)
                    ]),
  </code></pre>
  
  <p>It runs but if i scroll i receive this error:</p>
  
  <pre><code>I/flutter ( 4765): ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
  I/flutter ( 4765): The following message was thrown during layout:
  I/flutter ( 4765): A RenderFlex overflowed by 30 pixels on the bottom.
  I/flutter ( 4765):
  I/flutter ( 4765): The overflowing RenderFlex has an orientation of Axis.vertical.
  I/flutter ( 4765): The edge of the RenderFlex that is overflowing has been marked in the rendering with a yellow and
  I/flutter ( 4765): black striped pattern. This is usually caused by the contents being too big for the RenderFlex.
  I/flutter ( 4765): Consider applying a flex factor (e.g. using an Expanded widget) to force the children of the
  I/flutter ( 4765): RenderFlex to fit within the available space instead of being sized to their natural size.
  I/flutter ( 4765): This is considered an error condition because it indicates that there is content that cannot be
  I/flutter ( 4765): seen. If the content is legitimately bigger than the available space, consider clipping it with a
  I/flutter ( 4765): ClipRect widget before putting it in the flex, or using a scrollable container rather than a Flex,
  I/flutter ( 4765): like a ListView.
  I/flutter ( 4765): The specific RenderFlex in question is:
  I/flutter ( 4765):   RenderFlex#968e7 relayoutBoundary=up14 OVERFLOWING
  I/flutter ( 4765):   creator: Column ← Semantics ← DefaultTextStyle ← LayoutId-[&lt;_ToolbarSlot.middle&gt;] ←
  I/flutter ( 4765):   CustomMultiChildLayout ← NavigationToolbar ← DefaultTextStyle ← IconTheme ← Builder ←
  I/flutter ( 4765):   CustomSingleChildLayout ← ClipRect ← ConstrainedBox ← ⋯
  I/flutter ( 4765):   parentData: &lt;none&gt; (can use size)
  I/flutter ( 4765):   constraints: BoxConstraints(0.0&lt;=w&lt;=176.0, 0.0&lt;=h&lt;=20.3)
  I/flutter ( 4765):   size: Size(70.0, 20.3)
  I/flutter ( 4765):   direction: vertical
  I/flutter ( 4765):   mainAxisAlignment: start
  I/flutter ( 4765):   mainAxisSize: max
  I/flutter ( 4765):   crossAxisAlignment: center
  I/flutter ( 4765):   verticalDirection: down
  I/flutter ( 4765): ◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤
  I/flutter ( 4765): ════════════════════════════════════════════════════════════════════════════════════════════════════
  Reloaded 32 of 722 libraries in 2.887ms.
  </code></pre>
  
  <p>What i have to use instead of Column?</p>
  
  <p>Thanks</p>