Microsoft Corporation
Controlling a productivity application to integrate a revision stream and an undo stack to perform out of order undo operations

Abstract:

A computing system runs a productivity application that maintains an integrated, time ordered revision/undo stack. Entries in the revision/undo stack identify revision operations that a user has made to a document and corresponding undo operations that can be executed to undo the revision operation. The computing system detects an undo input indicative of a user actuating un undo actuator to undo a previous operation, that is prior to a most current operation that the user has performed. An operational transform system identifies an undo operation in the undo stack, corresponding to the revision that the user selected in the revision/undo stack. The operational transform system traverses the revision/undo stack to identify subsequent operations that were performed subsequent to the previous operation, and identifies one or more transforms to be applied to the undo operation based upon the identified subsequent operations. The operational transform system then transforms the undo operation, using the transformation function, and applies the transformed undo operation to the document.