People frequently experience difficulty switching between computer-mediated tasks. To help address this, we created WindowScape, a zooming window manager that uses implicit grouping to help users sort windows according to task. WindowScape was intended to provide a more flexible and intuitive grouping model than prior systems. We report on the design process leading up to the system, and alternative designs we explored. We describe a series of formative evaluations that resulted in significant modifications to our initial prototype, as well as a deployment study of the final version, where users lived with WindowScape on a day-to-day basis. Our results from this study reveal how users react to novel aspects of our system, including its particular uses of miniaturization and its approach to grouping. We also discuss the impact of a task-oriented approach to window management on other aspects of user behavior, and the implications of this for future system design.

The increasing popularity of personal reading devices raises the question of how best to support so-called active reading, which involves acts like annotation, note taking, etc. Prior research addressed this question by observing the active reading process, and identifying disparities between computers and paper as a reading medium. We extend this research by 1) investigating the problems that readers experience in their real world tasks, 2) inquiring about their requirements for an ideal reading technology, and 3) updating earlier studies of naturalistic reading behavior, which are several years old now. We present here the results of our investigation, which included a diary study, interviews, and participatory design workshops.

Active reading, involving acts such as highlighting, writing notes, etc., is an important part of knowledge workers' activities. Most computer-based active reading support seeks to replicate the affordances of paper, but paper has limitations, being in many ways inflexible. In this paper we introduce LiquidText, a computer-based active reading system that takes a fundamentally different approach, offering a flexible, fluid document representation built on multitouch input, with a range of interaction techniques designed to facilitate the activities of active reading. We report here on our design for LiquidText, its interactions and gesture vocabulary, and our design process, including formative user evaluations which helped shape the final system.

Could people use tagging to manage day-to-day work in their personal computing environment? Could tagging be sufficiently generic and lightweight to support diverse ways of working and, perhaps, support new and efficient practices for managing applications and accessing documents? We investigate these issues by implementing the TAGtivity system that enables users to tag resources in the context of their ongoing work. We deployed TAGtivity and studied users' tagging practices in their actual work places over a three week period. Our analysis of interviews and logs reveals that affordances of the TAGtivity system supported users in a variety of information and activity management tasks. These include new practices for managing emerging activities and ephemeral information and accessing documents across application data silos.

Non-expert users face a dilemma when making security decisions. Their security often cannot be fully automated for them, yet they generally lack both the motivation and technical knowledge to make informed security decisions on their own. To help users with this dilemma, we present a novel security user interface called Sesame. Sesame uses a concrete, spatial extension of the desktop metaphor to provide users with the security-related, visualized system-level information they need to make more informed decisions. It also provides users with actionable controls to affect a system's security state. Sesame graphically facilitates users' comprehension in making these decisions, and in doing so helps to lower the bar for motivating them to participate in the security of their system. In a controlled study, users with Sesame were found to make fewer errors than a control group which suggests that our novel security interface is a viable alternative approach to helping users with their dilemma.

We propose WindowScape, a window manager that uses a photograph metaphor for lightweight, post hoc task management. This is the first task management windowing model to provide intuitive accessibility while allowing windows to exist simultaneously in multiple tasks. WindowScape exploits users' spatial and visual memories by providing a stable thumbnail layout in which to search for windows. A function is provided to let users search the window space while maintaining a largely consistent screen image to minimize distractions. A novel keyboard interaction technique is also presented.