Drag-and-drop has become ubiquitous, both on desktop computers and touch-sensitive surfaces. It is used to move and edit the geometry of elements in graphics editors, to adjust parameters using controllers such as sliders, or to manage views (e.g., moving and resizing windows, panning maps). Reverting changes made via a drag-and-drop usually entails performing the reciprocal drag-and-drop action. This can be costly as users have to remember the previous position of the object and put it back precisely. We introduce the DnD-1 model that handles all past locations of graphical objects. We redesign the Dwell-and-Spring widget to interact with this history, and explain how applications can implement DnD-1 to enable users to perform reciprocal drag-and-drop to any past location for both individual objects and groups of objects. We report on two user studies, whose results show that users understand DnD-1 , and that Dwell-and-Spring enables them to interact with this model effectively.
