Moving towards making the clear completed button disappear when there are no completed tasks.

todo-example/emberjs/css/todos.css

@@ -396,6 +396,10 @@ body {
 
 	border:0px;
 }
+#todoapp #todo-stats button.none-completed {
+  display: none;
+}
+
 /* line 136 */
 #todoapp #todo-stats button:hover, #todoapp #todo-stats button:focus {
 	background: rgba(0, 0, 0, 0.15);

todo-example/emberjs/js/app.js

@@ -66,7 +66,10 @@ Todos.StatsView = Ember.View.extend({
   completedString: function() {
     var completed = this.get('completed');
     return completed + " completed" + (completed === 1 ? " item" : " items");
-  }.property('completed')
+  }.property('completed'),
+  updateCompletedButton: function () {
+    $('#todo-stats button').toggleClass('none-completed', this.get('completed') < 1);
+  }.observes('completed')
 });
 
 Todos.CreateTodoView = Ember.TextField.extend({