If one clicks on a QHeaderView's section, the header view will
sort the view by the respective column/row. By clicking multiple
times, one is able to toggle the sorting between ascending
and descending. Something that is NOT possible to do however is to
un-sort the view -- that is, to restore the model's original
sorting. This must be done via code, by asking the header or the
view to sort by section -1.
This commit adds new property to QHeaderView to make it possible
to unsort models. Basically, the sort indicator becomes a tri-state:
sort ascending, sort descending, unsort (sort by column -1).
[ChangeLog][QtWidgets][QHeaderView] Added the sortIndicatorClearable
property. Setting this property allows the user to clear the sort
indicator on a section, resetting the model to its default ordering.
Change-Id: Ibf4e280b2086b75ccd64d619ea4d70816dc3529f
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
Reviewed-by: David Faure <david.faure@kdab.com>
d982fdfca4