<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2007/12/20/setting-the-first-day-of-the-week-in-a-flex-datefield-controls-calendar/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="top"
        backgroundColor="white" viewSourceURL="srcview/index.html">

    <mx:Script>
        <![CDATA[
            import mx.events.SliderEvent;
            import mx.formatters.DateBase;

            private function dateField_labelFunc(item:Date):String {
                return dateFormatter.format(item);
            }

            private function slider_change(evt:SliderEvent):void {
                dateField.firstDayOfWeek = evt.value;
                dateField.open();
            }

            private function slider_dataTipFunc(value:Number):String {
                return DateBase.dayNamesShort[value];
            }
        ]]>
    </mx:Script>

    <mx:DateFormatter id="dateFormatter" formatString="MMM D, YYYY"/>

    <mx:ApplicationControlBar dock="true">
        <mx:Form styleName="plain">
            <mx:FormItem label="firstDayOfWeek:">
                <mx:HSlider id="slider"
                        minimum="0"
                        maximum="6"
                        liveDragging="true"
                        snapInterval="1"
                        tickInterval="1"
                        dataTipFormatFunction="slider_dataTipFunc"
                        change="slider_change(event);" />
            </mx:FormItem>
        </mx:Form>
    </mx:ApplicationControlBar>

    <mx:DateField id="dateField"
            labelFunction="dateField_labelFunc"
            firstDayOfWeek="{Days.MONDAY}" />

</mx:Application>