From 15e8f741fb3273c2b79004df27b74fe84dc192c5 Mon Sep 17 00:00:00 2001
From: Adam Barth <abarth@chromium.org>
Date: Tue, 25 Aug 2015 15:33:52 -0700
Subject: [PATCH] Properly track mimics that move in the tree

We weren't telling the new mimicable that we wanted to start mimicing it.
---
 packages/flutter/lib/widgets/mimic.dart | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/packages/flutter/lib/widgets/mimic.dart b/packages/flutter/lib/widgets/mimic.dart
index f8a7bbcafd..eb6aa22cf8 100644
--- a/packages/flutter/lib/widgets/mimic.dart
+++ b/packages/flutter/lib/widgets/mimic.dart
@@ -75,10 +75,7 @@ class Mimic extends GlobalKeyWatcher {
 
   void didUnmount() {
     super.didUnmount();
-    if (_mimicable != null) {
-      _mimicable.stopMimic();
-      _mimicable = null;
-    }
+    _stopMimic();
   }
 
   void didSyncWatchedKey(GlobalKey key, Widget widget) {
@@ -91,9 +88,18 @@ class Mimic extends GlobalKeyWatcher {
     _setMimicable(null);
   }
 
+  void _stopMimic() {
+    if (_mimicable != null) {
+      _mimicable.stopMimic();
+      _mimicable = null;
+    }
+  }
+
   void _setMimicable(widget) {
-    if (_mimicable == null && widget != null)
+    if (_mimicable != widget) {
+      _stopMimic();
       widget.startMimic();
+    }
     setState(() {
       _mimicable = widget;
     });