When the user drags an object in Scene Builder, SB invokes Node.startDragAndDrop().
Then it uses dragOver(), dragDropped() and dragDone() callbacks to perform some logic.

Sometimes on Linux, there is a dragOver() which is inserted between dragDropped()
and dragDone(). There is very unfrequent and happens only on Linux. On MacOS/Windows,
once dragDropped() has been called, dragOver() is no longer called.

After discussing with Pavel, this is not an expected behavior and should be fixed.

For Scene Builder, this not a critical issue (I added some logic to detect and discard spurious dragOver()).