This book promotes visual and functional consistency within and across the Windows operating system. Although following all of these guidelines is encouraged, you can adopt only the guidelines that best suit your application. By following these guidelines, you enable users of your application to transfer their skills and experience from one task to the next and to learn new tasks more easily.
However, adhering to these design guidelines does not guarantee usability. The guidelines are valuable tools, but to be part of an effective software design process, they must be combined with other factors such as design principles, task analysis, prototyping, and usability evaluation.
You can extend these guidelines, provided that you do so in the spirit of the principles on which they are based. It is important to maintain a reasonable level of consistency with the visual and behavioral aspects of the Windows interface. In general, avoid adding new elements or behaviors unless the interface does not otherwise support them. More importantly, avoid changing an existing behavior for common elements. A user builds up expectations about how an interface works. Inconsistencies confuse the user and add unnecessary complexity.
These guidelines supersede those issued for Microsoft Windows 95 and all previous releases, and are specific to the development of applications designed for Microsoft Windows 98, Microsoft Windows 2000 Professional, and Microsoft Windows 2000 Server. There is no direct relationship between these guidelines and those provided for other operating systems.
Fundamentals of Designing User Interaction
Design Specifications and Guidelines