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2.9. MULTIPLATFORM, INDUSTRY-STANDARD GUI STYLE
Our methodology can be modified to support design of interfaces in any OO GUI platform style, but at this moment the methodology fully and explicitly supports these four:
7Common User Access is a trademark of IBM Corp.
8Open Software Foundation is a trademark of Open Software Foundation, Inc.
9OSF, Motif, and OSF/Motif are trademarks of Open Software Foundation, Inc.
10X/Open is a registered trademark of X/Open Company LTD.
The multiplatform style common to those four GUI platform-specific styles is expressed most completely in the design guide by McFarland and Dayton (1995), which includes 256 supplements and extends design guidelines from all four platforms style guides. It is based not only on those four guides, but also on industry trends for GUI design, and on guidelines derived from successful GUI design at Bellcore and elsewhere. Designs following that multiplatform style are completely compatible with all four platform-specific styles.
Our methodology produces designs compatible with those multiple platforms mostly by
The multiplatform compatibility of the fundamental design guarantees that the details can be expressed in any of the four platform-specific styles and that the resulting detailed design can be easily translated into any of the other four styles. The industry-standard style allows this GUI to be immediately usable, at least in basic ways, by users having even a little experience with other industry-standard GUIs.
2.10. DESIGN FIRST FOR LESS-EXPERIENCED USERS
Our methodology designs first for less experienced users people who know only the industry-standard OO styles basic look and feel and the content domain of the GUI (e.g., hotels). The GUIs fundamental organization matches the users mental model of the domains data objects, their containment relations, and the actions that can be done to them. That organization forms the GUI universe in which users operate. The only other knowledge that users really need is knowledge of the basic laws of physics in that GUI universe, such as how to open, close, and move objects.
Take, for example, hotel desk clerks who are familiar with the industry standard, multiplatform, OO GUI style by virtue of either using another software product or brief training in the fundamentals common to all such GUIs. As long as the clerks know that hotels contain rooms and customers, and that customers contain reservations, they can do their work with a GUI that was designed via The Bridge. They will need to explore the GUI a bit, but they can do so safely and with confidence.
GUI features for expert users are important, but should be layered on top of, or carefully woven into, the fundamental GUI design. Part of the reason for this is that few people are always experts in all of the uses of any particular GUI. Most people use some aspects infrequently, so are novices in those aspects. At times of high cognitive load, only the most rudimentary and well-learned knowledge may be available (e.g., using the GUI while talking on the phone and gesturing to someone in your office). An example of an expert feature is showing objects in an indented hierarchical list so users can directly view and manipulate closed grandchild and great-grandchild objects without having to open their parents first (see the top left window in Figure 2.6).
At the other end of the spectrum are features for rank novices who lack knowledge of even the basics for using an industry-standard GUI. The best example is a wizard that steps users through a procedure for doing a task. A wizard should be layered on top of the OO design, so that users can escape the wizard at any time to directly manipulate the OO GUI themselves.
Features for experts and rank novices are two kinds of the polish that should be designed only at the end of Part 3 of The Bridge, so that the foundation design for less-experienced users is not distorted. Deciding when to shift the sessions focus toward such design details is part of the skill of a good facilitator.
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