Create an example app that demonstrates interactive coordination of an fn tree and a raw RenderObje…

sky/sdk/lib/widgets/basic.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'package:vector_math/vector_math.dart';
 
 import '../rendering/block.dart';
 import '../rendering/box.dart';
 import '../rendering/flex.dart';
 import '../rendering/object.dart';
@@ skipping 289 matching lines @@
 }
 
 class Positioned extends ParentDataNode {
   Positioned({
     String key,
     UINode child,
     double top,
     double right,
     double bottom,
     double left
-  }) : super(content,
+  }) : super(child,
              new StackParentData()..top = top
                                   ..right = right
                                   ..bottom = bottom
                                   ..left = left,
              key: key);
 }
 
 class Flex extends MultiChildRenderObjectWrapper {
 
   Flex(List<UINode> children, {
@@ skipping 74 matching lines @@
     root.src = src;
     root.requestedSize = size;
   }
 
   void insert(RenderObjectWrapper child, dynamic slot) {
     assert(false);
     // Image does not support having children currently
   }
 
 }
+
+class UINodeToRenderBoxAdapter extends RenderObjectWrapper {
+
+  UINodeToRenderBoxAdapter(RenderBox renderBox)
+    : this.renderBox = renderBox,
+      super(key: renderBox.hashCode.toString());
+
+  RenderBox get root => super.root;
+  RenderBox createNode() => this.renderBox;
+
+  final RenderBox renderBox;
+
+  void syncRenderObject(UINode old) {
+    super.syncRenderObject(old);
+    if (old != null) {
+      assert(old is UINodeToRenderBoxAdapter);
+      assert(root == old.renderBox);
+    }
+  }
+
+  void insert(RenderObjectWrapper child, dynamic slot) {
+    assert(false);
+    // UINodeToRenderBoxAdapter cannot have UINode children; by
+    // definition, it is the transition out of the UINode world.
+  }
+
+}