Roughly two grid rows — enough for vertical alignment and a tilt to read, without the pane's
top third being an empty rectangle.
OptionalmaxWidth
maxWidth?:number
Widest the preview box is drawn, in px. It still shrinks with a narrower pane.
Remarks
A cap, not a width: the pane is several cell-widths wide, and a preview stretched across all of
it stops reading as a cell — a filled format (accounting's * ) spans the whole span, and the
ends land a hand's width apart. This keeps the box near the width the value would actually be
shown at.
Height of the preview box.