Add an example of an app that manipulates both a RenderObject tree and has some fn logic in it.

sky/examples/widgets/container.dart

Index: sky/examples/widgets/container.dart
diff --git a/sky/examples/widgets/container.dart b/sky/examples/widgets/container.dart
index 437784078ade73ed332a35772e5d65e328441091..14b5663d13fd8ddee15c4004f82f36ff8907a00c 100644
--- a/sky/examples/widgets/container.dart
+++ b/sky/examples/widgets/container.dart
@@ -5,51 +5,44 @@
 import 'dart:sky' as sky;
 
 import 'package:sky/framework/rendering/box.dart';
+import 'package:sky/framework/rendering/flex.dart';
 import 'package:sky/framework/widgets/ui_node.dart';
 import 'package:sky/framework/widgets/wrappers.dart';
 
-import '../lib/solid_color_box.dart';
+class Rectangle extends Component {
 
-class Rectangle extends RenderObjectWrapper {
-  RenderSolidColorBox root;
-  RenderSolidColorBox createNode() =>
-      new RenderSolidColorBox(color, desiredSize: new sky.Size(40.0, 130.0));
+  Rectangle(this.color, { Object key }) : super(key: key);
 
-  final int color;
+  final Color color;
+
+  UINode build() {
+    return new FlexExpandingChild(
+      new Container(
+        decoration: new BoxDecoration(backgroundColor: color)
+      )
+    );
+  }
 
-  Rectangle(this.color, { Object key }) : super(key: key);
 }
 
 class ContainerApp extends App {
   UINode build() {
-    return new EventListenerNode(
-      new Block([
+    return new Flex([
+        new Rectangle(const Color(0xFF00FFFF), key: 'a'),
         new Container(
           padding: new EdgeDims.all(10.0),
           margin: new EdgeDims.all(10.0),
-          height: 100.0,
-          decoration: new BoxDecoration(backgroundColor: const sky.Color(0xFF00FF00)),
-          child: new Block([
-            new Container(
-              decoration: new BoxDecoration(backgroundColor: const sky.Color(0xFFFFFF00)),
-              height: 20.0
-            ),
-            new Image(src: "https://www.dartlang.org/logos/dart-logo.png",
-              size: new sky.Size(300.0, 300.0),
-              key: 1
-            ),
-          ])),
-      ]),
-      onPointerDown: _handlePointerDown,
-      onGestureTap: _handleGestureTap);
-  }
-
-  void _handlePointerDown(sky.PointerEvent event) {
-    print("_handlePointerDown");
-  }
-
-  void _handleGestureTap(sky.GestureEvent event) {
-    print("_handleGestureTap");
+          decoration: new BoxDecoration(backgroundColor: const Color(0xFFCCCCCC)),
+          child: new Image(src: "https://www.dartlang.org/logos/dart-logo.png",
+            size: new Size(300.0, 300.0),
+            key: 1
+          )
+        ),
+        new Rectangle(const Color(0xFFFFFF00), key: 'b'),
+      ],
+      direction: FlexDirection.vertical,
+      justifyContent: FlexJustifyContent.spaceBetween
+    );
   }
 }