Card "swipe-away" dismiss version 3: Uses BlockViewport

sky/sdk/lib/widgets/block_viewport.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 '../rendering/block.dart';
 import '../rendering/box.dart';
 import '../rendering/object.dart';
 import 'widget.dart';
 
 // return null if index is greater than index of last entry
@@ skipping 82 matching lines @@
         left = middle + 1;
       } else if (_offsets[middle] > offset) {
         right = middle - 1;
       } else {
         return middle;
       }
     }
     return right;
   }
 
-  bool _dirty = false;
+  bool _dirty = true;
 
   bool retainStatefulNodeIfPossible(BlockViewport newNode) {
     retainStatefulRenderObjectWrapper(newNode);
     if (startOffset != newNode.startOffset) {
       _dirty = true;
       startOffset = newNode.startOffset;
     }
     if (token != newNode.token || builder != newNode.builder) {
       _dirty = true;
       builder = newNode.builder;
       token = newNode.token;
       _offsets = <double>[0.0];
     }
     return true;
   }
 
   void syncRenderObject(BlockViewport old) {
     super.syncRenderObject(old);
     if (_dirty) {
       root.markNeedsLayout();
     } else {
       if (_currentChildCount > 0) {
         assert(_currentStartIndex >= 0);
         assert(builder != null);
         assert(root != null);
-        int lastIndex = _currentStartIndex + _currentChildCount;
+        int lastIndex = _currentStartIndex + _currentChildCount - 1;
         for (int index = _currentStartIndex; index <= lastIndex; index += 1) {
           Widget widget = builder(index);
           assert(widget != null);
           assert(widget.key != null);
           _Key key = new _Key.fromWidget(widget);
           Widget oldWidget = _childrenByKey[key];
           assert(oldWidget != null);
           assert(oldWidget.root.parent == root);
           widget = syncChild(widget, oldWidget, root.childAfter(oldWidget.root));
           assert(widget != null);
@@ skipping 143 matching lines @@
         nextSibling = widget.root;
       }      
     }
 
     _childrenByKey = newChildren;
     _currentStartIndex = startIndex;
     _currentChildCount = _childrenByKey.length;
   }
 
 }