gistfile1.diff

diff --git a/web/fc-app.dart b/web/fc-app.dart
index 9ab1b10..f8982d3 100644
--- a/web/fc-app.dart
+++ b/web/fc-app.dart
@@ -1,11 +1,30 @@
 import "package:polymer/polymer.dart";
 
 import "dart:html";
-import "dart:js";
 
 import "deck/deck.dart";
 import "tableau/tableau.dart";
 
+class ModelColumn extends Column {
+  final cards = new ObservableList();
+}
+
+class ModelCell extends Cell {
+  final cards = new ObservableList();
+}
+
+class ModelTower extends Tower {
+  final cards = new ObservableList();
+}
+
+class ModelTableau extends Tableau {
+  ModelTableau() {
+    columns = columns.map((_) => new ModelColumn()).toList(); 
+    cells = cells.map((_) => new ModelCell()).toList(); 
+    towers = towers.map((_) => new ModelTower()).toList(); 
+  }
+}
+
 @CustomTag("fc-app")
 class FcApp extends PolymerElement {
   @observable Tableau tableau;
@@ -14,7 +33,7 @@ class FcApp extends PolymerElement {
     Deck deck = new Deck();
     deck.shuffle();
 
-    tableau = new Tableau();
+    tableau = new ModelTableau();
     tableau.deal(deck);
   }
 
diff --git a/web/tableau/pile.dart b/web/tableau/pile.dart
index 7d8fdff..d868a54 100644
--- a/web/tableau/pile.dart
+++ b/web/tableau/pile.dart
@@ -5,11 +5,7 @@
 part of freecell.tableau;
 
 abstract class Pile {
-  ObservableList<Card> cards;
-
-  Pile() {
-    cards = new ObservableList<Card>();
-  }
+  final List<Card> cards = <Card>[];
 
   bool get isEmpty => cards.isEmpty;