<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/03/26/setting-the-menu-selection-mode-on-a-datagrid-control-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white" viewSourceURL="srcview/index.html">

    <mx:Array id="arr">
        <mx:Object c1="1a" c2="1b" />
        <mx:Object c1="2a" c2="2b" />
        <mx:Object c1="3a" c2="3b" />
        <mx:Object c1="4a" c2="4b" />
        <mx:Object c1="5a" c2="5b" />
        <mx:Object c1="6a" c2="6b" />
        <mx:Object c1="7a" c2="7b" />
    </mx:Array>

    <mx:ApplicationControlBar dock="true">
        <mx:Form styleName="plain">
            <mx:FormItem label="menuSelectionMode:">
                <mx:CheckBox id="checkBox" selected="false" />
            </mx:FormItem>
        </mx:Form>
    </mx:ApplicationControlBar>

    <mx:DataGrid id="dataGrid"
            dataProvider="{arr}"
            menuSelectionMode="{checkBox.selected}" />

</mx:Application>