<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/05/25/setting-the-text-color-on-a-disabled-numericstepper-control-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Style>
        NumericStepper {
            disabledColor: red;
        }
    </mx:Style>

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

    <mx:NumericStepper id="numericStepper"
            enabled="{checkBox.selected}" />

</mx:Application>