Transparency for Item Highlighting James Bowes David Dearman Ryan Perkins Faculty of Computing Science Dalhousie University Abstract In this paper, we introduce a system for reducing the visibility of infrequently used user interface items by increasing their transparency, thus increasing the visi- bility of frequently used items. We believe this system to be a superior alternative to the common method of completely removing infrequently used items from view. We discuss applications of this system to menus, toolboxes and desktop items, and issues associated with its implementation. Keywords: Transparency, menu, toolbox, user inter- face design, desktop 1 Introduction Menus, toolboxes and desktop items are used daily to provide the user with a great deal of selection. In many applications steps have been taken to reduce the number of options available to users with the goal of reducing the user’s confusion regarding selection options. We propose a system where menu, toolbox and desktop items that experience infrequent use would increase in transparency making them less visible while not com- pletely removing them from the screen. The majority of user interface (UI) research relating to transparency deals with its application for overlapping items without obscuring them. Staples [5] observes that items with increased transparency are easily distin- guishable from opaque ones. Therefore, rather than using transparency as a means of fitting more items on a screen, we propose to use transparency as an alterna- tive to the common technique of hiding infrequently used items. The inspiration for this topic comes from personalized menus in Microsoft Windows [3]. While personalized menus make frequently selected items more visible, they also completely remove less frequently used items from view (see Figure 1). These invisible items may become forgotten by the user. For example, if the user wants to perform a task that they perform infrequently, they may have forgotten that a menu item for that task exists. Some systems initially limit the user’s selection choices by not revealing items until they have been used. To use these items the user would actively have to seek them out amongst the hidden selections. With our proposed technique, the user’s initial selection will not be limited; the visibility of infrequently used items will be reduced, thus amplifying the visibility of fre- quently used items. This method also has the advantage of not repositioning any items; with personalized menus, the sizes of menus and the positions of items on them can change as items are revealed or hidden, mak- ing items slightly more difficult to find. Sears and Shneiderman [4] present another example of rearrang- ing menu items based on usage frequency. a) b) Figure 1. a) Regular Menu b) “ Personalized” Menu 2 Application and Implementation Our technique can be applied to a variety of user inter- face elements, including pull down menus, toolbox but- tons and desktop icons. It is anticipated that the most effective use would be with menus and toolboxes, since the items in these components are adjacent (see Figure 2). The adjacency of the items and the application of transparency gives the effect of “holes” in the menu or toolbox. Icons, however, could potentially spread across the desktop, making it difficult to compare the relative transparencies of two icons. The effectiveness of this technique with desktop icons will be dependent on their arrangement by the user. Furthermore, this technique’s effectiveness with desktop icons could be reduced by desktop backgrounds, which may contain