I’m not sure if this is the best way of doing it, but it seems to work. I don’t have the MAX Preview build installed, but I’m using Flex Builder 3 w/ SDK build 4.0.0.4250:

<?xml version="1.0" encoding="utf-8"?>
<Application name="FxTextArea_scroller_test"
        xmlns="http://ns.adobe.com/mxml/2009"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <Script>
        <![CDATA[
            import mx.components.FxVScrollBar;

            private function init():void {
                var vsb:FxVScrollBar = textArea.scroller.verticalScrollBar;
                var min:Number = vsb.minimum;
                var val:Number = vsb.value;
                var max:Number = vsb.maximum;
                lbl1.text = min.toString();
                lbl2.text = val.toString();
                lbl3.text = max.toString();
                progressBar.setProgress(val, max);
            }
        ]]>
    </Script>

    <ApplicationControlBar dock="true">
        <Form styleName="plain">
            <FormItem label="minimum:">
                <Label id="lbl1" />
            </FormItem>
            <FormItem label="value:">
                <Label id="lbl2" />
            </FormItem>
            <FormItem label="maximum:">
                <Label id="lbl3" />
            </FormItem>
            <FormItem>
                <ProgressBar id="progressBar"
                        mode="manual"
                        label="%1 / %2 (%3%%)" />
            </FormItem>
        </Form>
    </ApplicationControlBar>

    <FxTextArea id="textArea"
            width="100%"
            height="100%"
            enterFrame="init();">
        <content>
            <String source="data/lorem.html" />
        </content>
    </FxTextArea>

</Application>

I posted this as a new example, “Determining the current scroll position on an FxTextArea control in Flex Gumbo”.

Peter