treeViewer.addSelectionChangedListener(listener);
// Enable Drag & Drop Support
int ops = DND.DROP_COPY;
Transfer[] transfers = new Transfer[] { TextTransfer.getInstance() };
treeViewer.addDragSupport(ops, transfers, new SourceDragListener(
treeViewer));
// Handle Double Clicks on items
treeViewer.addDoubleClickListener(new IDoubleClickListener() {