<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2007/11/29/using-the-itemdoubleclick-event-to-open-nodes-in-a-flex-tree-control/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="horizontal"
        verticalAlign="middle"
        backgroundColor="white"
        creationComplete="init();">

<mx:Script>
        <![CDATA[
            import mx.events.ListEvent;

private function tree_itemDoubleClick(evt:ListEvent):void {
                var node:XML = tree.selectedItem as XML;
                var isOpen:Boolean = tree.isItemOpen(node);
                tree.expandItem(node, !isOpen);
            }
        ]]>
    </mx:Script>

<mx:XMLListCollection id="xmlListColl">
        <mx:source>
            <mx:XMLList>
                <node label="One">
                    <node label="One.1">
                        <node label="One.1.1">
                            <node label="One.1.1.1">
                                <node label="One.1.1.1.1" />
                            </node>
                        </node>
                    </node>
                    <node label="One.2" />
                    <node label="One.3" />
                </node>
                <node label="Two">
                    <node label="Two.1" />
                    <node label="Two.2" />
                    <node label="Two.3" />
                </node>
                <node label="Three" />
            </mx:XMLList>
        </mx:source>
    </mx:XMLListCollection>

<mx:ApplicationControlBar dock="true">
        <mx:CheckBox id="checkBox"
                label="doubleClickEnabled:"
                labelPlacement="left"
                selected="true" />
    </mx:ApplicationControlBar>

<mx:Tree id="tree"
            dataProvider="{xmlListColl}"
            labelField="@label"
            width="250"
            rowCount="6"
            doubleClickEnabled="{checkBox.selected}"
            itemDoubleClick="tree_itemDoubleClick(event);"
            showScrollTips="true" />

</mx:Application>

    本文转自 OldHawk  博客园博客，原文链接：http://www.cnblogs.com/taobataoma/archive/2008/01/10/1033994.html，如需转载请自行联系原作者