Visualizing histories for selective undo and redo

Today's interactive systems have provided sophisticated recovery tools that help protect users from their own mistakes. Although many graphical and direct manipulation user interfaces have undo/redo capabilities that allow the user to reverse erroneous actions, their undo/redo tools present only command history of textual representation which make if difficult for the user to identify the desired command and state. The authors present a way of visualizing the history of graphical editing systems, and an object-based history searching method for the graphical history, so that users would find it convenient and efficient to use undo/redo functions for their graphical manipulations. Considering that every change of the graphical editor window resembles an instance within a single continuum of visual history, they developed a visualized history view to this mechanism, listing "history snapshots"-the results to each command -to be presented as the command. They also found that it would be better if one provides several layouts of the history view to the user, in the case of different demands and situations. Considering the psychology of users when searching for a history command, they provide an object-grouped history searching method, in which only the history concerning a specified object is visible, for an efficient search. Supplemented with some other functions such as searching and turning over a comic strip, this visualized history will help users recall their operating history more easily and efficiently.