For some reasons lost in history, those methods simply ignore
the list of items passed to them, and always return NULL.
Of course, that's totally broken. Fix that by doing the same thing
that the respective (hidden) models did when calling mimeData().
Surprisingly enough, QTreeWidget has a proper implementation.
Task-number: QTBUG-25900
Change-Id: I99ca7b4d4f87f096fd9ff0b0cb4e58282aa9c26e
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: David Faure <david.faure@kdab.com>
ee17adebd2