Actionscript 3 将数据绑定到Flex 4.5中选定列表项鼠标上方的工具提示

我在flex中有一个图像，当我鼠标悬停在上面时，我希望能够根据列表中选择的项目从表中提取一些数据

图为：

    <s:Image source="@Embed('assets/icons/question-mark_16.png')"toolTip=""/>

以下是显示ArrayCollection的列表：

    private var availableReports:ArrayCollection = new ArrayCollection([
            {listOrder: 1, label: "Activity Summary Report", data: "actySummary", url: ""},
            {listOrder: 2, label: "Activity Report", data: "actyReport", url: ""},
            {listOrder: 3, label: "Performance Metrics and Data", data: "pmadReport", 
                url: properties.getProperty("config.links.pmd")},
            {listOrder: 4, label: "More Detailed Reports...", data: "moreReports", 
                url: properties.getProperty("config.links.reports")}
        ]);

    <s:List id="availableReportsList" width="100%"
    dataProvider="{availableReports}" selectedIndex="0"
    change="availableReportsList_changeHandler(event)"
    height="90">
    </s:List>

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这将从标签中提取数据

    <s:Image source="@Embed('assets/icons/question-mark_16.png')" toolTip="{availableReportsList.selectedItem.label}"/>