Volume 6A: Motif Programming Manual

exclusively by technical people who understand the environment and know how to work within it. But it is now time

to consider users who know absolutely nothing about computers and who don't want to−−they are only using your

software because they have to.

2.3 What Is Motif?

So, back to Motif. What is it and how can it help you solve your user−interface design goals? To start, Motif is a set of

guidelines that specifies how a user interface for graphical computers should look and feel. This term describes how

an application appears on the screen (the look) and how the user interacts with it (the feel).

the figure shows a Motif application.

A Motif application

The user interacts with the application by typing at the keyboard, and by clicking, selecting, and dragging various

graphic elements of the application with the mouse. For example, any application window can be moved on the screen

by moving the pointer to the top of the window's frame (the title bar), pressing and holding down a button on the

mouse, and dragging the window to a new location. The window can be made larger or smaller by pressing a mouse

button on any of the resize corners and dragging.

Most applications sport buttons that can be clicked with the mouse to initiate application actions. Motif uses clever

highlighting and shadowing to make buttons, and other components, look three−dimensional. When a button is

clicked on, it actually appears to be pressed in and released.

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A row of buttons across the top of most applications forms a menu bar. Clicking on any of the titles in the menu bar

pops up a menu of additional buttons. Buttons can also be arranged in palettes that are always visible on the screen.

When a button is clicked, the application can take immediate action or it can pop up an additional window called a

dialog box. A dialog box can ask the user for more information or present additional options.

This style of application interaction isn't new to most people, since the Apple MacIntosh popularized it years ago.

What is different about Motif is that the graphical user interface specification is designed to be independent of the

computer on which the application is running.

Motif was designed by the Open Software Foundation (OSF), a non−profit consortium of companies such as

Hewlett−Packard, Digital, IBM, and dozens of other corporations. OSF's charter calls for the development of

technologies that will enhance interoperability between computers from different manufacturers. Targeted

technologies range from user interfaces to operating systems.

Part of OSF's charter was to choose an appropriate windowing system environment that would enable the technology

to exist on as wide a range of computers as possible. It was decided that the OSF/Motif toolkit should be based on the

X Window System, a network−based windowing system that has been implemented for UNIX, VMS, DOS,

Macintosh, and other operating systems. X provides an extremely flexible foundation for any kind of graphical user

interface.

When used properly, the Motif toolkit enables you to produce completely Motif−compliant applications in a relatively

short amount of time. At its heart, though, Motif is a specification rather than an implementation. While most Motif

applications are implemented using the Motif toolkit provided by OSF, it would be quite possible for an application

implemented in a completely different way to comply with the Motif GUI. The specification is captured in two

documents: the Motif Style Guide, which defines the external look and feel of applications, and the Application

Environment Specification, which defines the application programmer's interface (API). Both books have been

published for OSF by Prentice−Hall and are available in most technical bookstores.

The Motif specifications don't have a whole lot to say about the overall layout of applications. Instead, they focus

mainly on the design of the objects that make up a user interface−−the menus, buttons, dialog boxes, text entry, and

display areas. There are some general rules, but for the most part, the consistency of the user interface relies on the

consistent behavior of the objects used to make it up, rather than their precise arrangement.

The Motif specification is broken down into two basic parts:

The output model describes what the objects on the screen look like. This model includes the shapes of

buttons, the use of three−dimensional effects, the use of cursors and bitmaps, and the positioning of windows

and subwindows. Although some recommendations are given concerning the use of fonts and other visual

features of the desktop's, Motif is flexible in most of these recommendations.

•

The input model specifies how the user interacts with the elements on the screen.•

The key point of the specification is that consistency should be maintained across all applications. Similar

user−interface elements should look and act similarly regardless of the application that contains them.

Motif can be used for virtually any application that interacts with a computer user. Programs as conceptually different

as a CAD/CAM package or an electronic mail application still use the same types of user−interface elements. When

the user interface is standardized, the user gets more quickly to the point where he is working with the application,

rather than just mastering its mechanics.

My experience with Microsoft Windows and my mother's new software demonstrates how far Motif has come in

reaching this goal. I was faced with a window system that I had literally never seen before and an operating system I

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