🚀 go-pugleaf

Jon,

There are two ways to accomplish.

One method is to use a single-cell table. However, a side-effect of
this is that since the headings are in the table flow, they will be
the last ones processed on a page when a TOC is generated. This may
result in some headings being out of order if you have a mixture of
boxed and unboxed heading on a page.

Another method is to use two paragraph tags together. The first tag
has a FrameBelow with a graphic box set to the appropriate height of
the background box. You then set the space below for this paratag to
be the negative value of the frame below height. Also set the Next Pgf
Tag to be the one for your actual heading. 

The next paragraph tag is for the actual heading. Set the space above
value to also be the negative value equal to the one in the preceding
paragraph tag. This will "back-up" the heading over top of the box in
the previous tag.

You may have to adjust the above/below values slightly to get things
perfectly centred in your box depending upon the font that you're
using (due to differing x-heights of fonts).