Step 1.5 of 3: AboutDialog uses scrollable AlertDialog (#49913)

packages/flutter/lib/src/material/about.dart

@@ -362,31 +362,29 @@ class AboutDialog extends StatelessWidget {
     final String version = applicationVersion ?? _defaultApplicationVersion(context);
     final Widget icon = applicationIcon ?? _defaultApplicationIcon(context);
     return AlertDialog(
-      content: SingleChildScrollView(
-        child: ListBody(
-          children: <Widget>[
-            Row(
-              crossAxisAlignment: CrossAxisAlignment.start,
-              children: <Widget>[
-                if (icon != null) IconTheme(data: Theme.of(context).iconTheme, child: icon),
-                Expanded(
-                  child: Padding(
-                    padding: const EdgeInsets.symmetric(horizontal: 24.0),
-                    child: ListBody(
-                      children: <Widget>[
-                        Text(name, style: Theme.of(context).textTheme.headline5),
-                        Text(version, style: Theme.of(context).textTheme.bodyText2),
-                        Container(height: 18.0),
-                        Text(applicationLegalese ?? '', style: Theme.of(context).textTheme.caption),
-                      ],
-                    ),
+      content: ListBody(
+        children: <Widget>[
+          Row(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: <Widget>[
+              if (icon != null) IconTheme(data: Theme.of(context).iconTheme, child: icon),
+              Expanded(
+                child: Padding(
+                  padding: const EdgeInsets.symmetric(horizontal: 24.0),
+                  child: ListBody(
+                    children: <Widget>[
+                      Text(name, style: Theme.of(context).textTheme.headline5),
+                      Text(version, style: Theme.of(context).textTheme.bodyText2),
+                      Container(height: 18.0),
+                      Text(applicationLegalese ?? '', style: Theme.of(context).textTheme.caption),
+                    ],
                   ),
                 ),
-              ],
-            ),
-            ...?children,
-          ],
-        ),
+              ),
+            ],
+          ),
+          ...?children,
+        ],
       ),
       actions: <Widget>[
         FlatButton(
@@ -408,6 +406,7 @@ class AboutDialog extends StatelessWidget {
           },
         ),
       ],
+      scrollable: true,
     );
   }
 }

packages/flutter/test/material/about_test.dart

@@ -469,6 +469,54 @@ void main() {
       findsNothing,
     );
   });
+
+  testWidgets("AboutDialog's contents are scrollable", (WidgetTester tester) async {
+    final Key contentKey = UniqueKey();
+    await tester.pumpWidget(MaterialApp(
+      home: Navigator(
+        onGenerateRoute: (RouteSettings settings) {
+          return MaterialPageRoute<dynamic>(
+            builder: (BuildContext context) {
+              return RaisedButton(
+                onPressed: () {
+                  showAboutDialog(
+                    context: context,
+                    useRootNavigator: false,
+                    applicationName: 'A',
+                    children: <Widget>[
+                      Container(
+                        key: contentKey,
+                        color: Colors.orange,
+                        height: 500,
+                      ),
+                    ],
+                  );
+                },
+                child: const Text('Show About Dialog'),
+              );
+            },
+          );
+        },
+      ),
+    ));
+
+    await tester.tap(find.text('Show About Dialog'));
+    await tester.pumpAndSettle();
+
+    // Try dragging by the [AboutDialog]'s title.
+    RenderBox box = tester.renderObject(find.text('A'));
+    Offset originalOffset = box.localToGlobal(Offset.zero);
+    await tester.drag(find.byKey(contentKey), const Offset(0.0, -20.0));
+
+    expect(box.localToGlobal(Offset.zero), equals(originalOffset.translate(0.0, -20.0)));
+
+    // Try dragging by the additional children in contents.
+    box = tester.renderObject(find.byKey(contentKey));
+    originalOffset = box.localToGlobal(Offset.zero);
+    await tester.drag(find.byKey(contentKey), const Offset(0.0, -20.0));
+
+    expect(box.localToGlobal(Offset.zero), equals(originalOffset.translate(0.0, -20.0)));
+  });
 }
 
 class FakeLicenseEntry extends LicenseEntry {