| In graphical user interfaces, direct manipulation consists in incremental actions that should be reversible. Typical examples include manipulating geometrical shapes in a vector graphics editor, navigating a document using a scrollbar, or moving and resizing windows on the desktop. As in many such cases, there will not be any mechanism to undo them, requiring users to manually revert to the previous state using a similar sequence of direct manipulation actions. The associated motor and cognitive costs can be high. We argue that proper and consistent mechanisms to support undo in this context are lacking, and present Dwell-and-Spring, an interaction technique that uses the metaphor of springs to enable users to undo direct manipulations. A spring widget pops up whenever the user dwells during a press-drag-release interaction, giving her the opportunity to either cancel the current manipulation or undo the last one. The technique is generic and can easily be implemented on top of existing applications to complement the traditional undo command. Empirical evaluation shows that users quickly adopt it as soon as they discover it. |
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