final Tree tree = treeViewerWithColumns.getTree();
final TreeEditor editor = new TreeEditor(tree);

tree.setLayoutData(new FillLayout());
tree.setHeaderVisible(true);
tree.setLinesVisible(true);
tree.addMouseListener(new MouseAdapter() {
	@Override
	public void mouseDoubleClick(MouseEvent e) {
		// Clean up any previous editor control
		Control oldEditor = editor.getEditor();
		if (oldEditor != null)
			oldEditor.dispose();

		if (tree.getSelectionCount() != 1) {
			return;
		}

		// Identify the selected row
		TreeItem[] selection = tree.getSelection();
		TreeItem item = selection[0];
		if (item == null)
			return;

		final SequenceContentImpl s = (SequenceContentImpl) item.getData();
		
		// The control that will be the editor must be a
		// child of the Table
		Text newEditor = new Text(tree, SWT.BORDER);
		newEditor.setText(s.getComment());
		newEditor.addModifyListener(new ModifyListener() {
			public void modifyText(ModifyEvent me) {
				Text text = (Text) editor.getEditor();
				s.setComment(text.getText());
			}
		});
		newEditor.selectAll();
		newEditor.setFocus();
		editor.setEditor(newEditor, item, COLUMN_INDEX_COMMENT);
	}
});

TreeColumn objectColumn = new TreeColumn(tree, SWT.NONE);
objectColumn.setText(getString("_UI_ObjectColumn_label"));
objectColumn.setResizable(true);
objectColumn.setWidth(250);

TreeColumn commentColumn = new TreeColumn(tree, SWT.NONE);
commentColumn.setText("Comment");
commentColumn.setResizable(true);
commentColumn.setWidth(200);

treeViewerWithColumns.setContentProvider(new AdapterFactoryContentProvider(adapterFactory));
treeViewerWithColumns.setLabelProvider(new SequenceTreeColumnLabelProvider(adapterFactory));
treeViewerWithColumns.setColumnProperties(new String[] { "a", "b" });
treeViewerWithColumns.setInput(s);

firePropertyChange(PROP_DIRTY);

TreeViewerFocusCellManager focusCellManager = new TreeViewerFocusCellManager(treeViewerWithColumns,
		new FocusCellOwnerDrawHighlighter(treeViewerWithColumns));
ColumnViewerEditorActivationStrategy actStrategy = new ColumnViewerEditorActivationStrategy(
		treeViewerWithColumns) {
	@Override
	protected boolean isEditorActivationEvent(ColumnViewerEditorActivationEvent event) {
		return super.isEditorActivationEvent(event)
				|| (event.eventType == ColumnViewerEditorActivationEvent.KEY_PRESSED && event.keyCode == SWT.CR);
	}
};

TreeViewerEditor.create(treeViewerWithColumns, focusCellManager, actStrategy,
		ColumnViewerEditor.TABBING_MOVE_TO_ROW_NEIGHBOR | ColumnViewerEditor.TABBING_VERTICAL
				| ColumnViewerEditor.KEYBOARD_ACTIVATION);

TreeViewerColumn viewerColumn = new TreeViewerColumn(treeViewerWithColumns, commentColumn);
viewerColumn.setLabelProvider(new DelegatingSequenceColumnLabelProvider(slp, COLUMN_INDEX_COMMENT));
viewerColumn.setEditingSupport(new EditingSupport(treeViewerWithColumns) {
	@Override
	protected void setValue(Object element, Object value) {
		if (element instanceof CommandImpl && !value.equals(((CommandImpl) element).getComment())) {
			Command save = SetCommand.create(getEditingDomain(), element,
					SequencePackage.Literals.SEQUENCE_CONTENT__COMMENT, value);
			getEditingDomain().getCommandStack().execute(save);
		}
	}

	@Override
	protected Object getValue(Object element) {
		return ((SequenceContentImpl) element).getComment();
	}

	@Override
	protected CellEditor getCellEditor(Object element) {
		return new TextCellEditor((Composite) treeViewerWithColumns.getControl());
	}

	@Override
	protected boolean canEdit(Object element) {
		return true;
	}
});