QHeaderView::setSortIndicatorShown(bool) sets all sections of the
header.

It would be nice to be able to set this on a section-by-section basis.

For columns that have no text in the header or data cells – only icons
– the sort indicator should not be shown (but the column shuold still
be sortable); otherwise it covers up the header icon for that section.

Apple's Mail.app is a good example of this. The user
can sort the messages table by the Read/Unread column, but the sort
indicator is hidden. If you click another header section that does have
text in the header (like "From" or "Subject", the sort indicator will
reappear in that section.

It would be nice if there was an overloaded method that takes a
section index parameter so that individual columns can be set.