<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/05/19/limiting-the-number-of-characters-a-user-can-type-into-a-numericstepper-controls-text-input-field-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white" viewSourceURL="srcview/index.html">

    <mx:ApplicationControlBar dock="true">
        <mx:Form styleName="plain">
            <mx:FormItem label="maxChars:">
                <mx:HSlider id="slider"
                        minimum="1"
                        maximum="3"
                        snapInterval="1"
                        tickInterval="1"
                        liveDragging="true" />
            </mx:FormItem>
        </mx:Form>
    </mx:ApplicationControlBar>

    <mx:NumericStepper id="numericStepper"
            minimum="0"
            maximum="10000"
            stepSize="10"
            maxChars="{slider.value}" />

</mx:Application>