The main purpose of the OSF/Motif Style Guide is to ensure consistency. Consistency is important both among applications and within a single application. Consistency helps the user transfer familiar skills to new situations. The user can apply the knowledge learned from one application to another application, reducing the amount of learning and subsequent recall. Consistency within applications facilitates exploration of new functions. When components work in a manner that is consistent with other components, the user will be less afraid to try new functions. The new functions will seem familiar, comfortable, and appropriate. The guidelines in the OSF/Motif Style Guide allow you to create applications that are consistent in a diverse market and that help your applications succeed in the marketplace.
Intraapplication consistency means the following:
For example, because Pulldown, Popup, and Option Menus are similar components, their operation and use should be similar. Choosing the proper component is described in Choosing Components. Component interaction is described in the reference section for each component and also in Interaction.
For example, pushing the top arrow in a ScrollBar should always move the ScrollBar up. Interaction is described in Interaction.
For example, clicking a button should always perform the same action. Note that even though the action is the same, the result of the action can depend on context. A button in a file editor can begin editing one of a number of files. The button need not always edit the same file; rather, its consistent action is to edit the selected file. Interaction is described in Interaction.
Components should not generally be added and removed as needed. This makes it difficult to quickly find the desired component. Instead, you should make unneeded components nonfunctional and indicate this by deemphasizing (graying out) their labels. Component layout is described in Layout.
The location of the mouse pointer should be determined by direct manipulation and should not be positioned arbitrarily by the application. Positioning the mouse pointer by the application causes the user to lose track of the pointer. Warping the pointer also causes problems with tablet style pointing devices that rely on absolute pointer positioning. The input model is described in Input Models.
Consistency among applications increases the user's sense of mastery. Experience with one application can be readily applied to another application, creating a positive transfer of knowledge. The task at hand, rather than learning a new application, becomes the focus of a computer session. When applications work in a manner that is consistent with other applications, users enjoy a feeling of immediate confidence in their ability to master the new program. Also, they are pleasantly surprised when trying new functions because, although new, the functions seem familiar.
Interapplication consistency means the following:
This does not mean that components look exactly the same, but that the internal layout of components should be the same. Elements of appearance such as color, size, and thickness of beveled edges are less important to application interoperability. Component design and layout are described in the reference section for each component and also in Component Design.
When interaction is different among applications, it confuses the user and makes it difficult to concentrate on the task of the application. This applies to the behavior of components, input methods, selection models, and keyboard navigation. Interaction is described in Interaction.
The user needs to be able to quickly find the proper component for each task. Organizing the components according to consistent guidelines helps the user do this. Application layout guidelines are described in Layout.