command

This paper offers a solution to the mode problem in computer sketch/notetaking programs. Conventionally, the user must specify the intended "draw" or "command" mode prior to performing a stroke. This necessity has proven to be a barrier to the usability of pen/stylus systems. We offer a novel Inferred-Mode interaction protocol that avoids the mode hassles of conventional sketch systems. The system infers the user's intent, if possible, from the properties of the pen trajectory and the context of the trajectory. If the intent is ambiguous, the user is offered a choice mediator in the form of a pop-up button. To maximize the fluidity of drawing, the user is entitled to ignore the mediator and continue drawing. We present decision logic for the inferred mode protocol, and discuss subtleties learned in the course of its development. We also present results of initial user trials validating the usability of this interaction design.

We introduce CrossY, a simple drawing application developed as a benchmark to demonstrate the feasibility of goal crossing as the basis for a graphical user interface. We show that crossing is not only as expressive as the current point-and-click interface, but also offers more flexibility in interaction design. In particular, crossing encourages the fluid composition of commands which supports the development of more fluid interfaces. While crossing was previously identified as a potential substitute for the classic point-and-click interaction, this work is the first to report on the practical aspects of implementing an interface based on goal crossing as the fundamental building block.

Modern applications provide interfaces for scripting, but many users do not know how to write script commands. However, many users are familiar with the idea of entering keywords into a web search engine. Hence, if a user is familiar with the vocabulary of an application domain, we anticipate that they could write a set of keywords expressing a command in that domain. For instance, in the web browsing domain, a user might enter <B>click search button</B>. We call expressions of this form keyword commands, and we present a novel approach for translating keyword commands directly into executable code. Our prototype of this system in the web browsing domain translates <B>click search button</B> into the Chickenfoot code <B>click(findButton("search"))</B>. This code is then executed in the context of a web browser to carry out the effect. We also present an implementation of this system in the domain of Microsoft Word. A user study revealed that subjects could use keyword commands to successfully complete 90% of the web browsing tasks in our study without instructions or training. Conversely, we would expect users to complete close to 0% of the tasks if they had to guess the underlying JavaScript commands with no instructions or training.

A new mechanism based on taps is introduced to separate the output from the application code in graphical interactive interfaces. The mechanism is implemented in GINA, an object-oriented application framework. Taps maintain a functional mapping from application data to interface objects that is described in a general-purpose programming language. Taps are triggered automatically by user actions. Compared to constraints or the MVC model, taps do not need execution or memory support from the application objects, at the expense of a performance penalty. Screen updates, which pose the largest performance problem, are minimized by checking for attribute changes and window visibility. A comparison operation is used to maintain structural consistency between hierarchies of application and interface objects. Taps can be defined interactively using formulas in a spreadsheet-like tool.