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
* be considered part of the open operation instead. Operations that are
	 * executed while a composite is open will first be executed and then added
	 * to the composite.
	 * </p>
	 * <p>
	 * Open operations cannot be nested. If this method is called when a
	 * different operation is open, it is presumed to be an application coding
	 * error and this method will throw an IllegalStateException.
	 * </p>
	 * 
	 * @param operation
	 *            the composite operation to be considered as the parent for all
	 *            subsequent operations.
	 * @param mode
	 *            the mode the operation is executing in. Can be one of
	 *            <code>EXECUTE</code>, <code>UNDO</code>, or
	 *            <code>REDO</code>. This determines what notifications are
	 *            sent.
	 */
	void openOperation(ICompositeOperation operation, int mode);
	/**
	 * <p>
	 * The specified operation has changed in some way since it was added to the
	 * operation history. Notify listeners with an OPERATION_CHANGED event.
	 * </p>
	 * 
	 * @param operation
	 *            the operation that has changed.
	 * 
	 */