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

    <mx:Array id="arr">
        <mx:Object col1="1" col2="A" col3="a" />
        <mx:Object col1="2" col2="B" col3="b" />
        <mx:Object col1="3" col2="C" col3="c" />
        <mx:Object col1="4" col2="D" col3="d" />
        <mx:Object col1="5" col2="E" col3="e" />
        <mx:Object col1="6" col2="F" col3="f" />
    </mx:Array>

    <mx:ApplicationControlBar dock="true">
        <mx:Form>
            <mx:FormItem label="rowCount:">
                <mx:HSlider id="slider"
                        minimum="0"
                        maximum="{arr.length+1}"
                        value="4"
                        liveDragging="true"
                        snapInterval="1"
                        tickInterval="1"
                        dataTipPrecision="0" />
            </mx:FormItem>
        </mx:Form>
    </mx:ApplicationControlBar>

    <mx:DataGrid id="dataGrid"
            dataProvider="{arr}"
            rowCount="{slider.value}" />

</mx:Application>