Instead, the focus of this paper is to explore and classify interactive characteristics of two-dimensional gestures as they are used in interactive systems. The benefits for the field are three-fold. First, such a classification describes one design space for the usage of two-dimensional gestures in interactive systems and thus presents possible choices to system designers. Second, empirical researchers can make use of such a classification to make systematic choices about aspects of gesture based systems that are worth studying. Finally, it can serve as a starting point for drawing parallels and exploring differences to gestures used in three-dimensional interfaces.

Inherent to typical computer applications is a very static relationship between internal data structures and presentation. In contrast, applications in our system (we call them interpretations), have to be able to deal with a much more dynamic relationship between those areas.

This paper motivates this idea, presents challenges faced by such an approach, explains a framework for designing and implementing such interpretations, and illustrates how exemplary interpretations make use of this framework.

The central idea of this work is to dissolve the static association between input marks and their interpretation and experiment with a dynamic, yet fluid, user driven association instead.

Our goal is to enable the fluid refinement and animation of graphically presented ideas while exposing the changes to objects as a whole and not just in discrete steps.

Translucency, as a mechanism, works particulary well if the object content is sufficiently spatially distributed.

Translucent patches lead to a unified view of windows, sub-windows and selections, and provide a base from which the tight connection between windows, their content, and applications can be dissolved. It forms one aspect of on-going work to support design activities that involve "marking" media, like paper and white boards, with computers. The central idea of that research is to allow the user to associate structure and meaning dynamically and smoothly to marks on a display surface.

It takes form as an interactive museum installation by which museum goers can explore Thangka related topics. Its multi-media database includes video records of Thangka paintings, catalogs of painting elements, live recording of a master painter's composition process, curatorial analyses, and images of Tibetan cultural life. The database is used by the sketchbook in two ways: (1) curators author presentation materials of Thangka related topics; (2) museum goers explore the curators presentations.

This paper will describe authoring and presentation tools that are used in the construction of the sketch book. The tools are based on an experimental stable storage system that provides versioning capabilities. The system is implemented in the Smalltalk-80 environment.