If you want to use Drag & Drop, you must also implement the Drop part. Note that the method I suggested in the linked thread does not use Drag & Drop at all; there we actually move the very widget rather than its visual copy.
May ways, some simpler than others:
simple:
more advanced, where we simultaneously Drag & Drop a widget:
move rotate
delete
pick another etc…
Too many ways to implement this - depends on the details. The most common way would be to handle it in the Player Controller where input stores a reference to the selected object and messages the appropriate interface whose functions the interactive objects implement.