Bug 153993 [Viewers] Common Baseclass for Tree/TableEditorImpl
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TreeEditorImpl.java
* Cancels the active cell editor, without saving the value 
     * back to the domain model.
     */
    public void cancelEditing() {
        if (cellEditor != null) {
            setEditor(null, null, 0);
            cellEditor.removeListener(cellEditorListener);
            CellEditor oldEditor = cellEditor;
            cellEditor = null;
            oldEditor.deactivate();
        }
    }
    /**
     * Start editing the given element. 
     * @param element
     * @param column
     */
    public void editElement(Object element, int column) {
        if (cellEditor != null) {
			applyEditorValue();
		}
        IStructuredSelection structuredSelection;
        if(element instanceof TreePath) {
        	structuredSelection = new TreeSelection((TreePath)element, viewer.getComparer());
        } else {
        	structuredSelection = new StructuredSelection(element);
        }
        setSelection(structuredSelection, true);
        Item[] selection = getSelection();
        if (selection.length != 1) {