2D User Interfaces

GUI Layout

Current graphical user interfaces (GUIs) describe how user interfaces elements (i.e., widgets) are placed inside a window via layout mechanisms. Layout becomes particularly relevant, when the size of the window or the orientation of the device is changed, as the layout mechanism also incorporates the resizing behaviour. This work investigates new layout mechanisms that are more powerful than all other alternatives, while still being easy-to-understand. Part of the work focuses on a new GUI builders to enable designers to use the new layouts for the creation of flexible GUI layouts. Older work explored a new technology, User Interface Façades, that let end-users adapt the user interface of arbitrary applications to their needs without resorting to coding, through drag-and-drop mechanims.

Text Entry & Learning

One line of research in this project concentrates on models to predict text entry rates for novice users. All other models focus on experts only, which provides only information about peak speeds, which many users never reach. Recent work in this project investigates new text entry methods for mobile devices, both button-based (Less-Tap) as well as on touch screens. Another line of research focuses on predictive models to simulate the transition of novices to experts, i.e., the learning of new text entry techniques

Our publications in this area

Errors in Occasionally Failing Systems

When interaction with computers, e.g., during text entry, humans make errors. Simultaneously, any technology may also make errors in interpreting input, e.g., due to the natural ambiguities of human language. Much research aims to predict and understand human performance in error-free text entry. Our research analyzes real-life text entry error correction behaviors. We then use our findings to develop a new model to predict the cost of error correction for character-based text entry technologies. We validate our model against quantities derived from the literature, as well as with a user study. Our study shows that the predicted and observed costs of error correction correspond well. We also present new methods that make it easier for users to deal with errors. Other research investigated errors in gestural user interfaces. See also W. Stuerzlinger's talk on Better User Interfaces for Occasionally Failing Technologies.

Group Selection

The direct manipulation of objects and efficient selection of objects is an integral part of modern user interfaces. Most systems support only rectangle selection and shift-clicking for group selection. In this project we investigate new group selection techniques, some of which is based on the way human perception naturally groups objects.

Touch Interfaces

We investigated different user interfaces touch-based user interfaces on interactive displays and also how critical touch is for mid-air interaction.

Latency in Pointing

This project investigates the effect of technical factors such as delays (commonly called latency), variations in delay (i.e. time jitter), spatial jitter, and several other factors on pointing performance, both in 2D and 3D. The trade-offs between these factors that are documented through our work allow input device designers to make better choices for high-performance input devices. We also present a predictive method to compensate for lag in a close-to-optimal manner.


Pen-based systems are becoming more common. Yet, how users use pens to follow a path is less well understood. Our research investigates pen steering motions towards new techniques for the interactive selection of arbitrary groups of objects. Other work investigated the differences between drawing with a mouse, touch, and a stylus.