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
*/
	public static boolean DEBUG_OPERATION_HISTORY_NOTIFICATION = false;
	/**
	 * This flag can be set to <code>true</code> if the history should print
	 * information to <code>System.out</code> whenever an unexpected condition
	 * arises. This flag should be used for debug purposes only.
	 */
	public static boolean DEBUG_OPERATION_HISTORY_UNEXPECTED = false;
	/**
	 * This flag can be set to <code>true</code> if the history should print
	 * information to <code>System.out</code> whenever an undo context is
	 * disposed. This flag should be used for debug purposes only.
	 */
	public static boolean DEBUG_OPERATION_HISTORY_DISPOSE = false;
	/**
	 * This flag can be set to <code>true</code> if the history should print
	 * information to <code>System.out</code> during the open/close sequence.
	 * This flag should be used for debug purposes only.
	 */
	public static boolean DEBUG_OPERATION_HISTORY_OPENOPERATION = false;
	/**
	 * This flag can be set to <code>true</code> if the history should print
	 * information to <code>System.out</code> whenever an operation is not
	 * approved. This flag should be used for debug purposes only.
	 */
	public static boolean DEBUG_OPERATION_HISTORY_APPROVAL = false;
	static final int DEFAULT_LIMIT = 20;
	/**
	 * the list of {@link IOperationApprover}s
	 */