pushDialog(navigator, (navigator) => new Dialog(...)).then((result) => process(result));

sky/sdk/example/address_book/lib/main.dart

@@ -68,7 +68,7 @@ class AddressBookApp extends App {
       child: new Icon(type: 'image/photo_camera', size: 24),
       backgroundColor: Theme.of(this).accentColor,
       onPressed: () {
-        navigator.push(new DialogRoute(builder: (navigator, route) {
+        showDialog(navigator, (navigator) {
           return new Dialog(
             title: new Text("Describe your picture"),
             content: new ScrollableBlock([
@@ -79,9 +79,7 @@ class AddressBookApp extends App {
             actions: [
               new FlatButton(
                 child: new Text('DISCARD'),
-                onPressed: () {
-                  navigator.pop();
-                }
+                onPressed: navigator.pop
               ),
               new FlatButton(
                 child: new Text('SAVE'),
@@ -91,7 +89,7 @@ class AddressBookApp extends App {
               ),
             ]
           );
-        }));
+        });
       }
     );
   }

sky/sdk/example/fitness/lib/feed.dart

@@ -214,10 +214,8 @@ class FeedFragment extends StatefulComponent {
   }
 
   void _handleActionButtonPressed() {
-    setState(() {
-      navigator.push(new DialogRoute(builder: (navigator, route) {
-        return new AddItemDialog(navigator);
-      }));
+    showDialog(navigator, (navigator) => new AddItemDialog(navigator)).then((route) {
+      navigator.pushNamed(route);
     });
   }
 
@@ -286,8 +284,7 @@ class AddItemDialog extends StatefulComponent {
         new FlatButton(
           child: new Text('ADD'),
           onPressed: () {
-            navigator.pop();
-            navigator.pushNamed(_addItemRoute);
+            navigator.pop(_addItemRoute);
           }
         ),
       ]

sky/sdk/example/stocks/lib/stock_settings.dart

@@ -45,26 +45,29 @@ class StockSettings extends StatefulComponent {
         _handleOptimismChanged(false);
         break;
       case StockMode.pessimistic:
-        navigator.push(new DialogRoute(builder: (navigator, route) {
+        showDialog(navigator, (navigator) {
           return new Dialog(
             title: new Text("Change mode?"),
             content: new Text("Optimistic mode means everything is awesome. Are you sure you can handle that?"),
-            onDismiss: navigator.pop,
+            onDismiss: () {
+              navigator.pop(false);
+            },
             actions: [
               new FlatButton(
                 child: new Text('NO THANKS'),
-                onPressed: navigator.pop
+                onPressed: () {
+                  navigator.pop(false);
+                }
               ),
               new FlatButton(
                 child: new Text('AGREE'),
                 onPressed: () {
-                  _handleOptimismChanged(true);
-                  navigator.pop();
+                  navigator.pop(true);
                 }
               ),
             ]
           );
-        }));
+        }).then(_handleOptimismChanged);
         break;
     }
   }

sky/sdk/lib/widgets/dialog.dart

@@ -2,13 +2,18 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
+
 import 'package:sky/theme/colors.dart' as colors;
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/default_text_style.dart';
 import 'package:sky/widgets/material.dart';
+import 'package:sky/widgets/navigator.dart';
 import 'package:sky/widgets/scrollable_viewport.dart';
 import 'package:sky/widgets/theme.dart';
 
+typedef Widget DialogBuilder(Navigator navigator);
+
 /// A material design dialog
 ///
 /// <https://www.google.com/design/spec/components/dialogs.html>
@@ -100,3 +105,14 @@ class Dialog extends Component {
 
   }
 }
+
+Future<dynamic> showDialog(Navigator navigator, DialogBuilder builder) {
+  Completer completer = new Completer();
+  navigator.push(new DialogRoute(
+    completer: completer,
+    builder: (navigator, route) {
+      return builder(navigator);
+    }
+  ));
+  return completer.future;
+}

sky/sdk/lib/widgets/navigator.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
+
 import 'package:sky/animation/animated_value.dart';
 import 'package:sky/animation/animation_performance.dart';
 import 'package:sky/animation/curves.dart';
@@ -14,7 +16,7 @@ typedef Widget RouteBuilder(Navigator navigator, RouteBase route);
 abstract class RouteBase {
   Widget build(Navigator navigator, RouteBase route);
   bool get isOpaque;
-  void popState() { }
+  void popState([dynamic result]) { assert(result == null); }
 }
 
 class Route extends RouteBase {
@@ -28,17 +30,16 @@ class Route extends RouteBase {
 }
 
 class DialogRoute extends RouteBase {
-  DialogRoute({ this.builder, this.callback });
+  DialogRoute({ this.completer, this.builder });
 
+  final Completer completer;
   final RouteBuilder builder;
-  Function callback;
 
   Widget build(Navigator navigator, RouteBase route) => builder(navigator, route);
   bool get isOpaque => false;
 
-  void popState() {
-    if (callback != null)
-      callback(this);
+  void popState([dynamic result]) {
+    completer.complete(result);
   }
 }
 
@@ -52,7 +53,8 @@ class RouteState extends RouteBase {
   Widget build(Navigator navigator, RouteBase route) => null;
   bool get isOpaque => false;
 
-  void popState() {
+  void popState([dynamic result]) {
+    assert(result == null);
     if (callback != null)
       callback(this);
   }
@@ -197,10 +199,10 @@ class NavigationState {
     historyIndex++;
   }
 
-  void pop() {
+  void pop([dynamic result]) {
     if (historyIndex > 0) {
       HistoryEntry entry = history[historyIndex];
-      entry.route.popState();
+      entry.route.popState(result);
       entry.fullyOpaque = false;
       historyIndex--;
     }
@@ -240,9 +242,9 @@ class Navigator extends StatefulComponent {
     });
   }
 
-  void pop() {
+  void pop([dynamic result]) {
     setState(() {
-      state.pop();
+      state.pop(result);
     });
   }
 

sky/sdk/lib/widgets/widget.dart

@@ -26,7 +26,6 @@ abstract class Key {
   factory Key(String value) => new StringKey(value);
   factory Key.stringify(Object value) => new StringKey(value.toString());
   factory Key.fromObjectIdentity(Object value) => new ObjectKey(value);
-  factory Key.unique() => new UniqueKey();
 }
 
 class StringKey extends Key {
@@ -45,14 +44,25 @@ class ObjectKey extends Key {
   int get hashCode => identityHashCode(value);
 }
 
-class UniqueKey extends Key {
-  UniqueKey() : super.constructor();
-  String toString() => '[$hashCode]';
+abstract class GlobalKey extends Key {
+  GlobalKey.constructor() : super.constructor(); // so that subclasses can call us, since the Key() factory constructor shadows the implicit constructor
+  factory GlobalKey({ String label }) => new LabeledGlobalKey(label);
+  factory GlobalKey.fromObjectIdentity(Object value) => new GlobalObjectKey(value);
 }
 
-class GlobalKey extends Key {
-  GlobalKey() : super.constructor();
-  String toString() => '[Global Key $hashCode]';
+class LabeledGlobalKey extends GlobalKey {
+  // the label is purely for documentary purposes and does not affect the key
+  LabeledGlobalKey(this._label) : super.constructor();
+  final String _label;
+  String toString() => '[GlobalKey ${_label != null ? _label : hashCode}]';
+}
+
+class GlobalObjectKey extends GlobalKey {
+  GlobalObjectKey(this.value) : super.constructor();
+  final Object value;
+  String toString() => '[GlobalKey ${value.runtimeType}(${value.hashCode})]';
+  bool operator==(other) => other is GlobalObjectKey && identical(other.value, value);
+  int get hashCode => identityHashCode(value);
 }
 
 /// A base class for elements of the widget tree