private void createDragSource() {
Transfer[] types = new Transfer[] { TextTransfer.getInstance() };
DragSource dragSource = new DragSource(tree, DND.DROP_COPY
| DND.DROP_MOVE);
dragSource.setTransfer(types);
dragSource.addDragListener(new DragSourceAdapter() {
@Override
public void dragSetData(DragSourceEvent event) {
List<MetaArtefactOperation> operations = new ArrayList<MetaArtefactOperation>();
for (TreeItem item : tree.getSelection()) {