How to draw a line under the first paragraph

Thanks Robin, that works fine. I've got another challenge now, which is to insert some spacing between those two text lines where the horizontal line is displayed. I was hoping to use leadingModel=box but it doesn't seem to make any difference for me.

Here's what I'm doing to display a horizontal line:

private function updateSkinPosition():void
    {
        var lastFlowLineOfFirstParagraph:TextFlowLine
            = findLastFlowLineOfFirstParagraph(textFlow.flowComposer);

        lastFlowLineOfFirstParagraph.getTextLine().addChild(skin);
        skin.y = 10;

        // we expect the skin to have update(width) method
        if (skin.hasOwnProperty("update"))
        {
            Object(skin).update(width);
        }

        // we offset the skin so that calculation inside the skin can assume that x=0 is the left
        // edge of the container
        skin.x = -lastFlowLineOfFirstParagraph.getBounds().left;
    }

and the skin just draws a line:

public function update(width:Number):void
    {
        graphics.clear();
        graphics.lineStyle(1, 0xff0000);
        graphics.moveTo(0, 0);
        graphics.lineTo(width, 0);
    }

Thanks for suggestions.