One of the design goals for Visual FoxPro 7.0 was to enable us to create applications that can be used by people with disabilities. The biggest change is support for the IAccessible interface that lets accessibility tools, such as screen readers, work with VFP applications.

Why does Microsoft care about this? There are two big reasons. First, more than 20 percent of the U.S. population has at least one disability, and the number increases with age. Second, software purchased by the U.S. government is required to be accessible to people with disabilities. If the U.S. government isn't the largest purchaser of software in the world, it's close.

Windows' accessibility features

Each new version of Windows includes more accessibility features. They fall into two broad classes: settings and tools. Settings let a user configure the computer. Windows includes settings for colors and font sizes, mouse pointers, keyboard response, and much more. Many of the accessibility-related settings are in the Control Panel Accessibility applet, but others are scattered throughout other Control Panel applets.

Accessibility tools let a user work with Windows and applications in a non-standard way. For example, the Narrator tool that comes with recent versions of Windows reads aloud text from applications. Magnifier uses part of the screen to enlarge the area around the mouse cursor. The On-Screen Keyboard provides an input device for users unable to manipulate a keyboard. Accessibility tools are found in Accessories > Accessibility.

There's another difference between accessibility settings and accessibility tools. You're pretty much limited to the settings that are built into Windows, but many other companies also provide accessibility tools. In fact, Microsoft says the tools it provides are mainly for initial setup, emergencies, and to demonstrate possibilities.

The Microsoft Web site has an excellent section devoted to accessibility: http:// www.microsoft.com/enable. The site includes information about Windows accessibility, Microsoft's efforts in this area, third-party accessibility tools, and more.

Accessibility and design

When I saw VFP 7.0's improvements in accessibility, I started thinking about how to design applications that take advantage of the improvements, but more importantly, are designed to accommodate users with disabilities.

In most cases, considering users with disabilities in designing a user interface results in a better interface for all users. The same principles that guide accessible design apply to overall user interface design: consistency, flexibility, and listening to the user.

The most important issue in designing accessible applications is to stay out of the way of accessibility tools and settings; i.e., go with the flow. Honor the user's color and mouse pointer choices, use system dialogs rather than your own whenever possible, use text rather than bitmaps of text, etc.

Consistency in an application is also a key consideration. Determine the standard way your application will work, and then apply it throughout. Ideally, your application should work the way other Windows applications work. While all these issues apply to all users, they're especially important for users who may have visual or motor impairments that make it hard for them to see large areas of the screen or easily move the pointer.

It's important not to require a mouse, since some people either can't use one or find it extremely difficult. Every required action should be available from the keyboard. Clearly, we can't insist on the reverse, since pointer devices don't provide alphanumeric input. However, you can assume a user who can't use a keyboard will have access to a tool like the On-Screen Keyboard, and you should make all navigational and command actions available using the mouse. Also, don't require the user to be able to hear. You must make sounds visible, as well.

One issue we don't generally think about as part of the design of an application is documentation. For users to learn your application, they need access to the documentation. The standard approaches may not work for users with disabilities. When possible, provide documentation in multiple formats.

The bottom line

Most of these design principles don't really address disability issues directly. They're simply good design practices, regardless of the audience. Keeping users with disabilities in mind as you design should help you produce applications that make all your users happier.