<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white" viewSourceURL="srcview/index.html">

    <mx:Script>
        <![CDATA[
            private function init():void {
                slider.value = dataGrid.headerHeight;
            }
        ]]>
    </mx:Script>

    <mx:Array id="arr">
        <mx:Object col1="1.One" col2="1.Two" />
        <mx:Object col1="1.One" col2="1.Two" />
        <mx:Object col1="1.One" col2="1.Two" />
        <mx:Object col1="1.One" col2="1.Two" />
        <mx:Object col1="1.One" col2="1.Two" />
    </mx:Array>

    <mx:ApplicationControlBar dock="true">
        <mx:Form styleName="plain">
            <mx:FormItem label="headerHeight:">
                <mx:HSlider id="slider"
                        minimum="0"
                        maximum="40"
                        snapInterval="1"
                        liveDragging="true" />
            </mx:FormItem>
            <mx:FormItem label="showHeaders:">
                <mx:CheckBox id="checkBox"
                        selected="true" />
            </mx:FormItem>
        </mx:Form>
    </mx:ApplicationControlBar>

    <mx:DataGrid id="dataGrid"
            dataProvider="{arr}"
            headerHeight="{slider.value}"
            showHeaders="{checkBox.selected}"
            initialize="init();">
        <mx:columns>
            <mx:DataGridColumn dataField="col1" />
            <mx:DataGridColumn dataField="col2" />
        </mx:columns>
    </mx:DataGrid>

</mx:Application>