Drag and drop works differently on MacOS.
To reproduce, use the attached application.
When the application is run on Windows, TransferMode.ANY is considered including TransferMode.MOVE, and onDragDone works properly, cleaning drag source string.
When the application is run on MacOS, drag source is cleaned only when drag and drop is started explicitly with TransferMode.MOVE (so TransferMode.ANY is considered a separate mode).

Affected tests:
tests/docsamples/hellodraganddrop_3