We have our own DropArea and DragArea which we should remove in favor of Qt upstream DropArea and Drag attached property. The Drag attached property is somewhat awkward as it needs to be used in conjunction with MouseArea drag capability. Maybe this is something that can be improved upstream.
Also, there's a DragHandler C++ class for starting a QDrag in Folder View, Kickoff, Kicker, etc which should be analyzed to see what features are needed upstream in Qt so it can be removed as well.
In that also consider touch usecase when you have conflicting interaction, like scroll, context menu, drag. We probably want touch flick to scroll but then you need something like long-press for drag and drop, etc.