Screen Layout

~ ~ The screen design is part of the user interface development, and is a result of the storyboarding described in Section . The various parts are shown in Figure . In the sections below, the various pieces are described, along with their required and expected functionality. This provides a good overview of how the user interface development had to be broken down to meet the design requirements.

Menu Bar

~ ~ The Menu Bar is located at the top of the screen, and provides access to several functions available throughout the design session. These functions are pulled together into several individual menus and placed in the Menu Bar to group them. The functions performed by the system's menus include File and Edit options, and context sensitive Help. The File options include starting a New design, continuing an Old design, Saving the current design, and Quitting the program. The Edit options include Undoing the last command and Changing the requirements, even in the middle of a design. This Menu Bar runs across the whole top of the screen. It is easily accessible and in the position expected for Motif applications. This consistency provides the user with a friendly framework, which should be well received by a user who has had previous exposure to Motif applications.

Drawing Area

~ ~ The Drawing Area, located in the middle of the screen, is the area where all of the graphical display is done. It displays the current tower design and must communicate a great deal of information to the user. Therefore, it needs to be large, occupying the central area of the screen, in order to keep the user's focus. Options available in this area include rotating the tower view to make it easier to see the actual positioning of pieces in the design. It is also in this area that the user specifies the positioning of components during the design.

Agent Display Area

~ ~ The Agent Display Area is located on the left side of the screen. It is the area where messages from each of the agents are accumulated individually. This area also provides a means of signaling when a new comment by a particular agent has been added, by highlighting that agent's buttons. It is used by the user to focus on a single aspect, and to get as much information as possible about that aspect without the interference of information concerning other aspects, such as that given by the Message Area (see Section ). The messages of all the agents are too many to view simultaneously, so the user must select an individual agent to get the information for a particular aspect. This information can then be used to make the next design decision.

Message Area

~ ~ The Message Area is located at the bottom of the screen. It contains messages from all of the agents, separated by a record of the user's actions. Messages are labeled to correspond to particular design steps by the user, so that the output can be matched to a particular user action, and to maintain focus on what is important for the next design decision being made. The messages are designed to offer alternative views to the user, so that the user can make informed choices for the next design decision. By placing the Message Area at the bottom of the screen, new information appears below the most important feature of the design system, the Drawing Area, but still occupies a large surface area to imply its importance.

Palette of Objects

~ ~ The Palette of Objects is located in the upper right. It contains the buttons to choose among the objects that the user can place into the current tower design. The user uses this palette to choose the component to add next. The palette reflects the current phase of the design (i.e., abstract, intermediate, or detailed) as put forth in Chapter . At the abstract level, abstract tower types are the only objects in the palette. At the intermediate level, various sized towers are selectable. At the detailed level, rods, braces, connectors, and platforms are available. The availability of objects specifically for each level leads the user through the decisions that need to be made to develop a complete design.

Requirements Display Area

~ ~ The Requirements Display Area is located in the center, on the right side of the screen, just below the Palette of Objects. It is placed here so that the requirements can be consulted when making a choice from the palette. The requirements need to be constantly displayed so that the user can maintain a focus on the goal of the designed tower. Focus is necessary when the user has to choose between conflicting suggestions from various agents. Placing the requirements in this position on the screen maintains their accessibility, but does not overstate their importance.

Other Information Area

~ ~ The Other Information Area is in the lower right corner, and is used to inform the user about the system's expectations. It gives information about where on the screen to look to make the next design decision. It may inform the user to choose from the file menu, or to select an item from the palette. An expert user could expect to find this information useless, so it is placed in a position which is not intrusive. It might be considered proper to place it near the place on the screen where the information is telling the user to act, but as the user is required to act in all of the other parts of the screen for one reason or another, it is not feasible to place it in any one place to help with this concern. So the optimal choice is to put it in a corner, out of the way of the other areas of the screen.

Pop-up Dialogs

~ ~ Various Pop-up Dialogs appear in the center of the screen when some aspect of the system needs immediate attention. These include the Requirements Selection dialog and various warnings about illegal or undesirable actions by the user. By appearing in the center of the screen, they offer an unambiguous suggestion for the user's next step. The user must react to the dialog immediately. After this immediate concern is handled, the pop-up disappears, and the design can continue.

The Whole Picture

~ ~ The pieces mentioned above are described separately, but must be integrated to show the whole system and to have the desired effect. The Message Area and Agent Display Area both provide complementary information from the agents. The Drawing Area, Palette of Objects, and Other Information Area guide the user's actions. All of the parts of the screen design have to be integrated properly to make the system function efficiently.