What Is User Interface Consistency?

User interface consistency is accomplished by meeting the expectations of the end user in the usability of the application. Most Visual Basic applications are created to allow the user to manipulate data (often from a database) in one manner or another. If the program makes it possible to manipulate the data in a way that seems clear and natural to the typical user, then it is consistent in its user interface.

The user interface does not consist only of forms and controls. In fact, there are three primary forms of user interfaces found in Visual Basic applications.

• Visual interface. The Visual interface is what is usually referred to as the user interface. This interface consists of forms, controls, Web pages, printouts, and any other form of communication between the application and the user, whether visible or audible.

• Data interface. The Data interface is used when opening or saving user data files, or when the application is in communication with a database system. The user cannot directly see this interface, although it can often be inferred through the presence of data files on a floppy disk, hard disk, or network server.

• Technical interface. Some interfaces are essential to your application, although they are rarely, if ever, noticed by the user. The Technical interface includes the use of configuration files and registry settings, and the ability of an application to be extended through the use of "add ins" (as can be done with Visual Basic itself).

Without these interfaces, an application could not successfully communicate with the user, and would be of no value. But the presence of these interfaces alone does not make an application's user interface consistent. If you start a new Visual Basic project, and drop a text box and command button on Form1, you have a working application with a user interface. But such an interface is insufficient to solve your user's complex business problems.

The user interface, the placement and order of forms and controls, and the ease of use of the application all indicate the type of organization found within the program. True user interface consistency exists in three realms: the realm of the user, the realm of the application itself, and realm of the system, where other software applications exist.

Consistency with the User

Often, the Visual Basic programmer will write an application either to replace an existing legacy application, or to automate a process presently done only on paper. Because of this, the users are already familiar with the process of carrying out the work to be done. The only thing they lack is a quality tool to assist them in that work. Is that not why you were called in the first place? Because your users may already be familiar with the goals of the application, it is your job to develop an application that clearly and consistently meets those goals. This is done by applying consistency and organization to the application.

When your program is complete, a user well trained in whatever business area to which your program applies should be able to sit right down and, without too much assistance, start using your application to solve problems. When the task that your application performs is complex, the amount of training will need to be increased. But even with an increased need for training, the user should be able to say, "Oh, that's obvious" throughout your application. A consistent user interface is the medium through which this understanding proceeds.

Consistency within the Application

When an application possesses consistency in presentation and internal organization, users can move from one part of the application to another and feel that they are using an application where all the parts were designed in the same way. This is not too difficult when a program is built by a single person, although projects that take one person more than six months to develop can show signs of an evolving understanding of the user interface. Adherence to consistency is especially important in applications developed by multiple programmers. Each programmer may think he or she has a better way of presenting information to the user than the other programmers do, but it will be only the user who suffers when a lack of understanding arises due to inconsistent organization.

Consistency with Other Applications

User interface consistency within an application also expands to include similarities with other applications familiar to the user. When you plan for this level of consistency within the application from the beginning, the user gets a head start on the usage of the program by approaching it with some understanding of how "those Windows programs" work. For example, many applications include a toolbar with standard menus and buttons for cut, copy, and paste operations, as shown in Figure 4-1.

If your application supports these features, you should be consistent with other applications in the wording and position of the menus, and in the images used in the toolbar. Meeting your users' expectations though this brand of user interface consistency increases their understanding of the new solutions wrought by your hand.