Direct touch manipulations enable the user to interact with the on-screen content in a direct and easy manner closely mimicking the spatial manipulations in the physical world. However, they also suffer from well-known issues of precision, occlusion and an inability to isolate different degrees of freedom in spatial manipulations. We present a set of interactions, called Rock & Rails, that augment existing direct touch manipulations with shape-based gestures, thus providing on-demand gain control, occlusion avoidance, and separation of constraints in 2D manipulation tasks. Using shape gestures in combination with direct-manipulations allows us to do this without ambiguity in detection and without resorting to manipulation handles, which break the direct manipulation paradigm. Our set of interactions were evaluated by 8 expert graphic designers and were found to be easy to learn and master, as well as effective in accomplishing a precise graphical layout task.

Groups of users often have shared information needs -- for example, business colleagues need to conduct research relating to joint projects and students must work together on group homework assignments. In this paper, we introduce WeSearch, a collaborative Web search system designed to leverage the benefits of tabletop displays for face-to-face collaboration and organization tasks. We describe the design of WeSearch and explain the interactions it affords. We then describe an evaluation in which eleven groups used WeSearch to conduct real collaborative search tasks. Based on our study's findings, we analyze the effectiveness of the features introduced by WeSearch.