diff --git a/src/core/widget.js b/src/core/widget.js
index f872b5470..b1d1fe258 100644
--- a/src/core/widget.js
+++ b/src/core/widget.js
@@ -76,8 +76,7 @@
 
         shouldUpdate: null,
 
-        update: function () {
-        },
+        update: null,
 
         beforeUpdate: null,
 
diff --git a/src/core/wrapper/layout.js b/src/core/wrapper/layout.js
index 5d4fdc470..20f68850c 100644
--- a/src/core/wrapper/layout.js
+++ b/src/core/wrapper/layout.js
@@ -71,12 +71,13 @@ BI.Layout = BI.inherit(BI.Widget, {
         var self = this;
         var frag = BI.Widget._renderEngine.createFragment();
         var hasChild = false;
-        BI.each(this._children, function (i, widget) {
-            if (widget.element !== self.element) {
-                frag.appendChild(widget.element[0]);
+        for (var key in this._children) {
+            var child = this._children[key];
+            if (child.element !== self.element) {
+                frag.appendChild(child.element[0]);
                 hasChild = true;
             }
-        });
+        }
         if (hasChild === true) {
             this.appendFragment(frag);
         }
@@ -268,19 +269,13 @@ BI.Layout = BI.inherit(BI.Widget, {
         if (!child.shouldUpdate) {
             return null;
         }
-        return child.shouldUpdate(this._getOptions(item)) === true;
+        return child.shouldUpdate(this._getOptions(item));
     },
 
     updateItemAt: function (index, item) {
         if (index < 0 || index > this.options.items.length - 1) {
             return;
         }
-
-        var child = this._children[this._getChildName(index)];
-        var updated;
-        if (updated = child.update(this._getOptions(item))) {
-            return updated;
-        }
         var del = this._children[this._getChildName(index)];
         delete this._children[this._getChildName(index)];
         this.options.items.splice(index, 1);
@@ -367,7 +362,14 @@ BI.Layout = BI.inherit(BI.Widget, {
 
     patchItem: function (oldVnode, vnode, index) {
         var shouldUpdate = this.shouldUpdateItem(index, vnode);
-        if (shouldUpdate === true || (shouldUpdate === null && !this._compare(oldVnode, vnode))) {
+        var child = this._children[this._getChildName(index)];
+        if (shouldUpdate) {
+            return child._update(this._getOptions(vnode), shouldUpdate);
+        }
+        if (shouldUpdate === null && !this._compare(oldVnode, vnode)) {
+            // if (child.update) {
+            //     return child.update(this._getOptions(vnode));
+            // }
             return this.updateItemAt(index, vnode);
         }
     },
diff --git a/ui/less/var.less b/ui/less/var.less
index e55756a31..c89fa87cc 100644
--- a/ui/less/var.less
+++ b/ui/less/var.less
@@ -2,4 +2,4 @@
 
 @fontUrl: '@{webUrl}font/'; //图片的基本地址
 @imageUrl: '@{webUrl}images/1x/'; //图片的基本地址
-@image2xUrl: '@{webUrl}images/2x/'; //2倍图片的基本地址
\ No newline at end of file
+@image2xUrl: '@{webUrl}images/2x/'; //2倍图片的基本地址