Bug 94400 [Undo] - After successful undo, should operation be disposed by framework if it cannot be redone?
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/operations/DefaultOperationHistory.java
List approvers = Collections.synchronizedList(new ArrayList());
	/**
	 * a map of undo limits per context
	 */
	private Map limits = Collections.synchronizedMap(new HashMap());
	/**
	 * the list of {@link IOperationHistoryListener}s
	 */
	List listeners = Collections.synchronizedList(new ArrayList());
	/**
	 * the list of operations available for redo, LIFO
	 */
	private List redoList = Collections.synchronizedList(new ArrayList());
	/**
	 * the list of operations available for undo, LIFO
	 */
	private List undoList = Collections.synchronizedList(new ArrayList());
	/**
	 * a key that is used to synchronize access between the undo and redo
	 * history
	 */
	final Object undoRedoHistoryKey = new Object();
	/**
	 * An operation that is "absorbing" all other operations while it is open.
	 * When this is not null, other operations added or executed are added to
	 * this composite.
	 * 
	 */
	private ICompositeOperation openComposite = null;
	/**