When the user drops data on a DropTarget, the application which defines the DragSource
must provide the dropped data by implementing dragSetData. In the dragSetData, the application
must support all the data types that were specified in the DragSource#setTransfer method.
After the drop has completed successfully or has been aborted, the application which defines the
DragSource is required to take the appropriate cleanup action. In the case of a successful
move operation, the application must remove the data that was transferred.