Bug 258736 [Viewers] [JFace] setUseHashLookUp() and multiple occurrences of same domain object in TreeViewer
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TreeViewer.java
});
			treeControl.addListener(SWT.SetData, new Listener() {
				public void handleEvent(Event event) {
					if (contentProviderIsLazy) {
						TreeItem item = (TreeItem) event.item;
						TreeItem parentItem = item.getParentItem();
						int index = event.index;
						virtualLazyUpdateWidget(
								parentItem == null ? (Widget) getTree()
										: parentItem, index);
					}
				}
			});
		}
	}
	protected ColumnViewerEditor createViewerEditor() {
		return new TreeViewerEditor(this,null,new ColumnViewerEditorActivationStrategy(this),ColumnViewerEditor.DEFAULT);
	}
	/*
	 * (non-Javadoc) Method declared in AbstractTreeViewer.
	 */
	protected Item newItem(Widget parent, int flags, int ix) {
		TreeItem item;
		if (parent instanceof TreeItem) {
			item = (TreeItem) createNewRowPart(getViewerRowFromItem(parent),
					flags, ix).getItem();
		} else {
			item = (TreeItem) createNewRowPart(null, flags, ix).getItem();
		}
		return item;