BI-45290 fix: 组件1滚动到底部后复制，会显示空白或一闪而过空白

src/core/wrapper/layout.js

@@ -299,16 +299,22 @@ BI.Layout = BI.inherit(BI.Widget, {
     addItems: function (items, context) {
         var self = this, o = this.options;
         var fragment = BI.Widget._renderEngine.createFragment();
+        var wrapper = this._getWrapper();
         var added = [];
         BI.each(items, function (i, item) {
             var w = self._addElement(o.items.length, item, context);
             self._children[self._getChildName(o.items.length)] = w;
             o.items.push(item);
             added.push(w);
-            fragment.appendChild(w.element[0]);
+            var node = w.element[0];
+            var childNodes = wrapper[0].childNodes;
+            // BI-45290 wrapper中已包含的node不需要再次添加（添加可能导致内部滚动条位置重置）
+            if (!BI.contains(childNodes, node)) {
+                fragment.appendChild(node);
+            }
         });
         if (this._isMounted) {
-            this._getWrapper().append(fragment);
+            wrapper.append(fragment);
             BI.each(added, function (i, w) {
                 w._mount();
             });
@@ -605,4 +611,4 @@ BI.Layout = BI.inherit(BI.Widget, {
 
     }
 });
-BI.shortcut("bi.layout", BI.Layout);
+BI.shortcut("bi.layout", BI.Layout);