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The undo function is not accessory, but still it has not been introduced to mobile devices in an appropriate way. Undo is still shaped to fit text editing, and it has changed a little only for graphical editing so far. In this paper, we report the results of a survey with which we investigated why and how to add this functionality to regular mobile phones -- not only to smartphones or high-end handheld devices. Our respondents suggested an undo model that is linear, sequential, with variable granularity (according to the context of use) and requiring confirmation before execution (both to improve awareness and avoid additional mistakes).
Marco Loregian (Mon,) studied this question.