I can help. If you want to send me what you are using now I can fix it up.
The basic idea is that you create a colorfill around the text that is set to fill the parent object. You can do that a few different ways, (Anchor, Grid, VerticalFlow, Form, etc)
i.e.
<LayoutInput>
<FormLayoutInput Left=”Parent,0″ Top=”Parent,0″ Horizontal=”Fill” />
</LayoutInput>