Kill onDidMount()/onDidUnmount() in favour of just overriding the relevant methods.

sky/sdk/lib/framework/editing2/editable_text.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 '../fn2.dart';
 import '../theme/colors.dart';
 import 'dart:async';
 import 'editable_string.dart';
 
 class EditableText extends Component {
 
+  EditableText({Object key, this.value, this.focused})
+      : super(key: key, stateful: true);
+
   // static final Style _cursorStyle = new Style('''
   //   width: 2px;
   //   height: 1.2em;
   //   vertical-align: top;
   //   background-color: ${Blue[500]};'''
   // );
 
   // static final Style _composingStyle = new Style('''
   //   text-decoration: underline;'''
   // );
 
   EditableString value;
   bool focused;
+
+  void syncFields(EditableText source) {
+    value = source.value;
+    focused = source.focused;
+  }
+
   Timer _cursorTimer;
   bool _showCursor = false;
 
-  EditableText({Object key, this.value, this.focused})
-      : super(key: key, stateful: true) {
-    onDidUnmount(() {
-      if (_cursorTimer != null)
-        _stopCursorTimer();
-    });
-  }
-
   void _cursorTick(Timer timer) {
     setState(() {
       _showCursor = !_showCursor;
     });
   }
 
   void _startCursorTimer() {
     _showCursor = true;
     _cursorTimer = new Timer.periodic(
         new Duration(milliseconds: 500), _cursorTick);
   }
 
+  void didUnmount() {
+    if (_cursorTimer != null)
+      _stopCursorTimer();
+    super.didUnmount();
+  }
+
   void _stopCursorTimer() {
     _cursorTimer.cancel();
     _cursorTimer = null;
     _showCursor = false;
   }
 
   UINode build() {
     if (focused && _cursorTimer == null)
       _startCursorTimer();
     else if (!focused && _cursorTimer != null)
@@ skipping 32 matching lines @@
     //   children.add(new Container(
     //     key: 'cursor',
     //     // style: _cursorStyle
     //     ));
 
     return new Paragraph(
       text: hack
     );
   }
 }