When hiding any widget that is not a panel, it is correct to clear
subfocus. In case clearFocus() has been called, the result is that
focusItem() / focusWidget() points to 0, which is correct. Upon
reactivation, nothing gains input focus. When changing focus, the
following setSubFocus() call will ensure subfocus points to the new
widget.
When hiding a panel, however, it's essential that subfocus within
that panel is not cleared, otherwise, when re-showing the panel,
nothing will have focus, whereas the expected behavior is that focus
is restored to the last item that had focus, i.e., the focusItem()
a.k.a. subfocus widget.
Task-number: QTBUG-22256
Change-Id: I84d849a505764e074e1369fef923cef1ad5c0b1e
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
bfb569b6e7