pub fn heading(column: &Column<'_>, style: &TableStyle) -> StringExpand description
The heading, in capitals, with the caret if the table is ordered by this column.
Capitals because the header strip’s label is set that way at every host.
A column sorted but not sortable
still gets its caret. Both combinations mean something, which is why the
description holds the two fields apart: a list ordered by a key the user
cannot change is a real thing, and the caret is how it says so.