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
* 
	 * @see org.eclipse.core.commands.operations.IOperationHistory#getOperation(org.eclipse.core.commands.operations.IUndoContext)
	 */
	public IUndoableOperation getRedoOperation(IUndoContext context) {
		Assert.isNotNull(context);
		synchronized (undoRedoHistoryKey) {
			for (int i = redoList.size() - 1; i >= 0; i--) {
				IUndoableOperation operation = (IUndoableOperation) redoList
						.get(i);
				if (operation.hasContext(context)) {
					return operation;
				}
			}
		}
		return null;
	}
	/*
	 * Consult the IOperationApprovers to see if the proposed undo should be
	 * allowed.
	 */
	private IStatus getUndoApproval(IUndoableOperation operation,
			IAdaptable info) {
		
		
		
		final IOperationApprover[] approverArray = (IOperationApprover[]) approvers
				.toArray(new IOperationApprover[approvers.size()]);
		for (int i = 0; i < approverArray.length; i++) {
			IOperationApprover approver = approverArray[i];
			IStatus approval = approver.proceedUndoing(operation, this, info);