When we are trying to query the data inside the DrtopTargetListener.dragEnter it finishes in calling a native copyDraggingDataForFormat: call. This call uses a static cache: sPasteboardTypes and sPasteboardData which should contain the types and data, cached from the pasteboard which we received in NSView with the DnD events. However, these caches are updated only from the performDragOperation call, which is only called after the drop.

It should be decided if we need to copy the data at all. The possible fix would be cache a reference to the NSPasteboard and work with it directly inside the copyDraggingDataForFormat: