Bug 94438 [Undo] - javadoc - clarify operation remaining in history for undo/redo with INFO/WARNING
The javadoc for the IOperationHistory#undo(...) redo(...) methods is very explicit about the operation remaining in the history on CANCEL and ERROR status, and that it is moved between undo/redo histories when ok. Some minor clarifications: The lack of an explicit statement about INFO and WARNING makes one wonder what happens to the operation. It remains in the history in this case also... Technically, on OK status the operation is not guaranteed to move between the stacks. If it cannot redo after undoing, or cannot undo after redoing, it won't be transferred to the other stack, but in effect will be removed from the history.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/operations/IOperationHistory.java
*            undo or redo history for the specified context. Must not be
	 *            negative.
	 */
	void setLimit(IUndoContext context, int limit);
	/**
	 * <p>
	 * Undo the most recently executed operation in the given context
	 * </p>
	 * 
	 * @param context 
	 *            the context to be undone
	 * @param monitor 
	 *            the progress monitor to be used for the undo, or
	 *            <code>null</code> if no progress monitor is provided.
	 * @param info 
	 *            the IAdaptable (or <code>null</code>) provided by the
	 *            caller in order to supply UI information for prompting the
	 *            user if necessary. When this parameter is not
	 *            <code>null</code>, it should minimally contain an adapter
	 *            for the org.eclipse.swt.widgets.Shell.class.
	 * 
	 * @return the IStatus indicating whether the undo succeeded.
	 * 
	 * <p>
	 * The severity code in the returned status describes whether the operation
	 * succeeded and whether it remains in the history. <code>OK</code>
	 * severity indicates that the undo operation was successful and that the
	 * operation has been placed on the redo history. Listeners will receive the
	 * <code>UNDONE</code> notification.
	 * </p>