title: Bottom Overflow in Expansion Panel
body: <p>Can anyone help to decipher the exception that I keep running into? I am not sure what to attempt next in order to fix the overflow as the panel expands. I've tried wrapping it into a flexible widget but that doesn't seem to fix the issue. </p>
  
  <p>Here's a quick gif showing the error: <a href="https://imgur.com/itIYV8s" rel="noreferrer">https://imgur.com/itIYV8s</a></p>
  
  <p>Here is my exception: </p>
  
  <pre><code>flutter: ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY 
  ╞═════════════════════════════════════════════════════════
  flutter: The following message was thrown during layout:
  flutter: A RenderFlex overflowed by 74 pixels on the bottom.
  flutter:
  flutter: The overflowing RenderFlex has an orientation of Axis.vertical.
  flutter: The edge of the RenderFlex that is overflowing has been marked 
  in the rendering with a yellow and
  flutter: black striped pattern. This is usually caused by the contents 
  being too big for the RenderFlex.
  flutter: Consider applying a flex factor (e.g. using an Expanded widget) 
  to force the children of the
  flutter: RenderFlex to fit within the available space instead of being 
  sized to their natural size.
  flutter: This is considered an error condition because it indicates that there is content that cannot be
  flutter: seen. If the content is legitimately bigger than the available space, consider clipping it with a
  flutter: ClipRect widget before putting it in the flex, or using a scrollable container rather than a Flex,
  flutter: like a ListView.
  flutter: The specific RenderFlex in question is:
  flutter:   RenderFlex#ac136 OVERFLOWING
  flutter:   creator: Column ← DecoratedBox ← ConstrainedBox ← Container ← AnimatedContainer ← Container ←
  flutter:   Column ← DefaultTextStyle ← AnimatedDefaultTextStyle ← _InkFeatures-[GlobalKey#04b41 ink renderer]
  flutter:   ← NotificationListener&lt;LayoutChangedNotification&gt; ← CustomPaint ← ⋯
  flutter:   parentData: &lt;none&gt; (can use size)
  flutter:   constraints: BoxConstraints(w=363.0, h=0.4)
  flutter:   size: Size(363.0, 0.4)
  flutter:   direction: vertical
  flutter:   mainAxisAlignment: spaceBetween
  flutter:   mainAxisSize: max
  flutter:   crossAxisAlignment: center
  flutter:   verticalDirection: down
  flutter: ◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤
  flutter: ════════════════════════════════════════════════════════════════════════════════════════════════════
  flutter: Another exception was thrown: A RenderFlex overflowed by 74 pixels on the bottom.
  </code></pre>
  
  <p>Here is my code:</p>
  
  <pre><code>new SingleChildScrollView(
      child: new Card(
      margin: EdgeInsets.all(0.0),
      elevation: 2.0,
      color: MyApp.getTheme().canvasColor,
      child: new Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: &lt;Widget&gt;[
          new ListTile(
              title: new Text("FB", style: new TextStyle(
                fontWeight: FontWeight.bold,
              ),),
              subtitle: new Text("Facebook, Inc."),
              onTap: () {
                setState(() {
                  if (this._bodyHeight == 200.0) {
                    this._bodyHeight = 0.0;
                  } else {
                    this._bodyHeight = 200.0;
                  }
                });
              },
              trailing: new FlatButton(
                shape: new RoundedRectangleBorder(
                  borderRadius: new BorderRadius.all(new Radius.circular(20.0)),
                ),
                onPressed: () {
                  setState(() {
                    mode++;
                    if (mode == 1) {
                      text = "+0.80%";
                    } else if (mode == 2) {
                      text = "+1.41";
                    } else {
                      text = "513.3B";
                      mode=0;
                    }
                  });
                },
                child: new Text("+1.41", style: new TextStyle(
                  color: Colors.white,
                ),),
                color: Colors.green,
              )
          ),
          new Container(
            child: new AnimatedContainer(
              child: new Column(
               mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: &lt;Widget&gt;[
                  new Text(""),
                  new Padding(
                    padding: new EdgeInsets.only(bottom: 5.0),
                    child: new Column(
                      children: &lt;Widget&gt;[
                        new Divider(),
                        new Row(
                          mainAxisAlignment: MainAxisAlignment.end,
                          children: &lt;Widget&gt;[
                            new FlatButton(
                              onPressed: () {
                                setState(() {
                                  if (this._bodyHeight == 200.0) {
                                    this._bodyHeight = 0.0;
                                  } else {
                                    this._bodyHeight = 200.0;
                                  }
                                });
                               },
                              child: new Text(
                                "CANCEL",
                                style: new TextStyle(
                                  color: Colors.grey,
                                ),
                              ),
                            ),
                            new FlatButton(
                              onPressed: null,
                              child: new Text(
                                 "SAVE",
                                style: new TextStyle(
                                  color: MyApp.getTheme().indicatorColor,
                                ),
                              ),
                            ),
                          ],
                        ),
                      ],
                    ),
                  )
                ],
              ),
              width: 400.0,
              curve: Curves.easeInOut,
              duration: const Duration(milliseconds: 500),
              height: _bodyHeight,
              color: MyApp.getTheme().canvasColor,
            ),
          ),
        ],
      ),
    ),
  ),
  </code></pre>
  
  <p>Thank you so much!</p>