A QVariant can only be converted to a QByteArray if it has user type
QMetaType::QByteArray or QMetaType::QString. The way it stood, we
always tried to convert the mime data to a QByteArray, and
then put the result into a QVariant. This would fail if the mime
data contained e.g a QPixmap.
This patch will inspect what kind of data the QMimeData contains, and
convert it to a QVariant using the expected API.
Backport of 6d3c483
Task-number: QTBUG-57428
Task-number: QTBUG-63660
Change-Id: I09b4a94aef7b52773e1a79c468ead71b36dfbfc5
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
6c1a2224f3