Backtracking in a multiple-window hypertext environment

Multi-window interfaces allow users to work on logically independent taks simultaneously in different sets of windows and to move among these logical tasks at will (e.g., through selecting a window in a different task). Hypertext backtracking should be able to treat each logical task separately. Combining all traversals in a single chronological history log would violate the user's mental model and cause disorientation. In this paper we introduce task-based backtracking, a technique for backtracking within the various logical tasks a user may be working on at any given time. We present a preliminary algorithm for its implementation. We also discuss several ramifications of multi-window backtracking including the types of events history logs must record, deleting nodes from history logs that appear in multiple logical tasks, and in general the choices hypermedia designers face in multi-window environments.