I just ran into various issues with the drag indicator graphic on
different systems.
On my Arch system with KDE6, any drag just shows the red cross
indicating that something can't be dropped. However, the drop works
fine. Regardless of what kind of data is dropped or accepted. I also
checked that the issue occurs in the MonkeyTester with the latest jfx
commit on master.
On my Ubuntu 24.04 with Gnome and macOS 27, there is only positive
indicator feedback if the mode is set to copy. The same drag operation
from A to B within a JavaFX app shows correctly with TransferMode.COPY,
but does not show any indicator with TransferMode.MOVE. I.e.
startDragAndDrop(TransferMode.MOVE) and
acceptTransferModes(TransferMode.MOVE) does not work, but for COPY it
does. COPY_OR_MOVE and ANY do also work, so it seems limited to MOVE.
On Windows, everything works as expected, so it is not a general issue.
