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Go backArticlesFace to face with Open Look

Reprinted from Byte, issue 13/88, pp. 286-296.

Can a new graphical interface make Unix friendly after all these years?

For years now, the Unix operating system has been like an athlete with potential – it has great talent but somehow has never lived up to expectations on the playing field.

While Unix is one of the most capable and powerful operating systems available, it still has a very small installed base (about 350,000 licenses and some 1 million users) compared to the MS-DOS operating system (more than 10 million users) or even the Macintosh Finder (close to 2 million). Many industry observers would agree that the main problem with Unix has been its lack of an accessible, easy-to-use interface.

In April 1988, AT&T announced a new graphical user interface called Open Look, destined to be the user interface for Unix System V version 4.0, the converged version of the three most popular variants of Unix: System V, Berkeley (BSD) 4.2, and Xenix. Designed for AT&T by Sun Microsystems, and based on technology licensed from Xerox, Open Look was designed to be independent of the hardware and software on which it runs; as such, it can be used with operating systems other than Unix.

The graphical interface story

The development of graphical user interfaces can be traced to commercial products such as the Xerox Star, Smalltalk, and the Macintosh; to academic projects such as the Andrew system from Carnegie-Mellon; to research systems such as Diamond and Sapphire; and to many applications in areas like CAD and desktop publishing.

The roots of all these systems go back to work done at Xerox’s Palo Alto Research Center (PARC) in the 1970s. Among the more influential of the Xerox systems are Smalltalk, the Star (and its successor ViewPoint), the Bravo Editor, and the Cedar development environment. These systems introduced many of the ideas that have come to be taken for granted as the basic elements of graphical user interfaces: windows, icons, menus, the desktop metaphor, and direct manipulation of objects on the screen by the user. The designers of the Star, in particular, placed great emphasis on the consistency of the user interface.

In the early 1980s, the designers of the Apple Macintosh took those ideas and combined them in a design tuned for a specific machine, market, and price point. The Macintosh had a single-process operating system and a small screen. This led to a user interface based on a single top-of-the-screen menu bar used by whatever program was currently active. The designers envisioned an interface that was simple and accessible to nontechnical people. This emphasis on simplicity also led to the choice of a single-button mouse.

The Open Look user interface for Unix builds on and enhances both of these traditions – the consistency of the Star and the simplicity of the Macintosh. Beyond specific features, however, the major significance of Open Look is that it is not tied to a particular computer or operating system.

The “Open” in Open Look

The Xerox Star was a tightly integrated, closed system. The hardware, operating system, windowing system, user interface, and applications were all built by the same company, so consistency was ensured.

Similarly, the Macintosh was a closed system, though Apple broke the applications out of the bundle. As independent software developers began to supply applications for the Macintosh, consistency across applications emerged as a crucial issue. Apple addressed this issue by publishing user-interface guidelines and creating a culture that encouraged application developers to follow the conventions.

With the advent of open systems like the Mac II, hardware as well as software is now available from companies other than Apple. Meanwhile, a variety of graphics-oriented system software (e.g., Windows and the Presentation Manager) is now available for 8086/80286/80386 machines.

In graphics-based systems, the trend from tightly integrated, single-vendor systems toward loosely integrated, multivendor systems has important consequences for user interfaces. The designers of the Star took the position that the hardware should be designed specifically to fit the software. The designers of the Macintosh also designed their look and feel with reference to a particular operating system, display, and mouse.

Open Look takes this evolution to the next step. It was designed from the start to accommodate different keyboards, mice, and screen resolutions. The interface is not tied to a particular piece of hardware, operating system, or windowing system, so it is possible for applications to have a consistent look and feel, regardless of what hardware or operating system they happen to be running on.

First look at Open Look

In Open Look, the display screen is called the workspace. The workspace contains windows and icons representing application programs. An application typically consists of one main window (in which the application’s data is displayed) and several pop-up windows that you use to manipulate the data.

Figure 1: A typical Open Look screen with edit and draw applications. Each application consists of one main menu (which you can resize using the L-shaped corners) and several pop-up windows that you use to manipulate the data.
This image can be zoomedFigure 1: A typical Open Look screen with edit and draw applications. Each application consists of one main menu (which you can resize using the L-shaped corners) and several pop-up windows that you use to manipulate the data.
Figure 1 shows a typical Open Look screen with sample applications called Draw and Write. Notice the L-shaped corners on the applications’ windows, suggesting picture mounts from a photo album. By clicking and dragging these mounts, you can resize a window from any corner.

At the top of each application window is the header, which contains the name of die application and a window mark that closes the application when you click it.

Below the header is the application’s control area, which provides access to the application’s main functions, such as opening and closing files. The control area typically consists of a single row of buttons. You “push” these buttons by moving the mouse pointer over it and clicking the Select mouse button. (For an explanation of Open Look’s approach to mice, see the text box Open Season for Mice.)

As you can see in figure 1, there are two styles of buttons: Those with a single, heavy shadow are simple buttons, representing a single command. Those with a double shadow are button stacks, representing several related commands.

To perform the default action on a button stack, you click the Select mouse button. Pressing the Menu mouse button calls up the menu associated with the stack. The Edit button’s menu in figure 1 has been opened up in this way. Notice that the menu itself contains buttons and button stacks. By using the two types of buttons in combination, an application can support far more commands than it could display on the control panel.

Below the control area is the pane, in which the application displays its data. The form that data takes is up to the application; usually it is text, a drawing, or a spreadsheet.

To the right of the pane is a scroll bar that lets you move the contents of a document within the pane. As you can see in figure 1, the Open Look scroll bar resembles an elevator riding on a cable that is anchored at either end. Clicking on the top arrow moves you one line toward the top of the document; clicking on the bottom arrow moves you one line toward the bottom. Because the arrow buttons are located next to each other on the elevator instead of at either end of the scroll bar, you need only move the mouse a short distance to reverse directions.

To jump directly to the beginning or end of the file, click on the top or bottom cable anchors, respectively. Finally, you can move to any part of the document by pressing in the middle of the elevator and dragging.

Property windows

Open Look’s debt to the Xerox Star is evident in its use of property windows that let you view and modify the properties of any object you can see on the screen.

Figure 2: A typical Open Look property window for a word processing application. Settings whose boxes are closed together are exclusive – you can only choose one at a time. With settings whose boxes are separated, you can choose as many as you want.
This image can be zoomedFigure 2: A typical Open Look property window for a word processing application. Settings whose boxes are closed together are exclusive – you can only choose one at a time. With settings whose boxes are separated, you can choose as many as you want.
To change an object’s properties, you first select the object of interest. Then choose Properties from the appropriate menu (which will change depending on the application and the object you select). This will bring up a window with controls that you can use to modify the properties of the object. All property windows work in exactly the same way, regardless of which object you are changing. For example, you could select a word in a word processing program and change its font, select the main window of an application and change the application’s background color, or select the screen background and change a global property such as the volume of the system bell. Figure 2 shows a typical property window for a word processing application.

The first two lines in the property window of figure 2 are examples of settings that let you choose among predefined choices. When you select a setting, its border becomes outlined in bold. Settings whose borders touch are exclusive – only one choice may be on at a given time. Settings whose borders do not touch are nonexclusive – you can toggle each choice on and off independently of the others. Below the settings is a text-entry field, and below that is a sliding control that lets you choose quickly from a range of values.

All property windows have a special control, known as the pushpin, at the right of the window header. When the pin is on its side, as in figure 2, the window will disappear when you click the OK button. If you click on a pushpin, it pops into the hole next to it. The window will remain until you dismiss it by clicking on the window mark in the header. Using the pushpin lets you perform multiple operations (such as changing font characteristics of various words throughout a document) without having the window disappear after each action.

An application may also have pushpins on menus, thus allowing the menu to be pinned up for repeated use. Figure 1 shows examples of both pinned and unpinned menus.

Additional pop-ups

Figure 3: Open Look’s three-dimensional notice windows alert you to actions that could result in loss of data.
This image can be zoomedFigure 3: Open Look’s three-dimensional notice windows alert you to actions that could result in loss of data.
A special type of pop-up window is the notice, which asks you to confirm operations that would result in the loss of data. Notices appear to project from the button that prompted their appearance, as shown in figure 3. This “projection” acts as a visual prompt.

Figure 4: The Open Look help window, called by pointing to an object on the screen and pressing a Help key, contains a help message and a help lens, with a snapshot of the object for which you have requested help.
This image can be zoomedFigure 4: The Open Look help window, called by pointing to an object on the screen and pressing a Help key, contains a help message and a help lens, with a snapshot of the object for which you have requested help.
Open Look provides help through a standard help window (see figure 4) that appears when you point at an object on the screen and press the Help key on your keyboard (which will vary from system to system).

Next to the help message is the help lens, a magnifying glass that contains a snapshot of the object for which you have requested help. As you move the mouse pointer from object to object and press the Help key, both the image in the lens and the help text are updated.

Design goals

The main goals of the Open Look design were to provide the following: good visual design; balance among simplicity, consistency, and efficiency; device independence; and interoperability with other widely used interfaces.

One of the most challenging aspects of visual design is the use of color. The problem is to use color so it emphasizes useful distinctions and adds interest to the visual scene without producing a neon “Las Vegas” effect.

Some user interfaces show each visual element – buttons, scroll bars, window headers, and so on – in a different color, resulting in a random clutter of bright colors. In contrast, Open Look allows you to choose the colors for three areas of the user interface: the background of the screen, the background of each window, and the currently selected object. This use of color serves several purposes. The backgrounds of the windows are colored with neutral tones so that they will not overwhelm whatever information the application is displaying. Also, since a single background color is used for all the windows of a given application, you can tell at a glance which pop-up window goes with which application.

Against this neutral background, the eye is naturally drawn to the brightly colored selection (e.g., the block of yellow text in figure 1), which is the focus of the user’s attention.

Open Look provides several palettes from which you can choose the colors of the screen background, window backgrounds, and the current selection. The colors in each palette have been chosen by the graphic designer so that they go well together. This approach accommodates individual tastes while ensuring that the overall effect will be pleasing and the text will still be readable.

Simplicity, consistency, and efficiency are the basic principles that guided the Open Look design. When you’re doing a new task, you want the interface to be simple. If the interface is similar to that of a task with which you are already familiar, learning will be easier. And when you are doing a task over and over, you want the interface to be as efficient as possible.

It is hard to overemphasize the importance of consistency. Consistency lets you learn many applications and switch easily among them.

Several aspects of the Open Look design reflect this emphasis on consistency. Throughout the system and across applications, a given mouse button is used for only one function. We aimed for visual consistency in the design of controls: Buttons and settings look the same, regardless of whether they appear in a pop-up menu or in a window. The help window is another example of consistency: You can point to any object on the screen and get help, regardless of whether it is a standard element of the system (such as the pushpin) or an application-specific object such as a particular button.

Figure 5: While earlier graphical interfaces pioneered the direct manipulation of graphics objects, Open Look extends this, allowing you to select and drag arbitrary pieces of text as well.
This image can be zoomedFigure 5: While earlier graphical interfaces pioneered the direct manipulation of graphics objects, Open Look extends this, allowing you to select and drag arbitrary pieces of text as well.
Open Look has taken many other well-established conventions of graphical user interfaces and applied them in a more consistent way. For example, in Open Look, we extended the familiar selection paradigm to include the screen background, so you can select multiple windows and move or close them in a single operation. Another example: While earlier interfaces let you manipulate graphics objects directly, Open Look lets you select and drag arbitrary pieces of text as well (see figure 5).

Efficiency is easier to measure than simplicity or consistency. The fewer moves needed to perform a task, the more efficient the interface. This means minimizing keystrokes, mouse travel, and the need to switch back and forth between the keyboard and the mouse.

Minimizing mouse travel becomes more important as more systems use large screens. One way to reduce mouse motion is by using pop-up menus. In Open Look, each region of the screen – the workspace, the window background, scroll bars, and each application pane – has its own pop-up menu with relevant buttons. Instead of having to move all the way to the control area, you simply press the Menu mouse button, which effectively brings a control area to wherever the pointer happens to be.

Another way that Open Look minimizes mouse travel is by jumping the mouse pointer to a default button when a pop-up window (such as a notice) appears. If you click on the default button in the window, the pointer jumps back to its original position – saving two mouse motions.

A more subtle aspect of efficiency is allowing users to take advantage of the multitasking capability of an operating system like Unix. Take the problem of how to indicate that a window is busy and will not respond to input. Most systems change the mouse pointer into an hourglass or timer. In a single-tasking system such as the Macintosh, this is appropriate, since you can’t do anything else until the active window is finished. In multitasking systems, however, the hourglass is only visible when the pointer is over the window that is busy. This approach requires you to keep the pointer in the busy window so you can see when it becomes responsive again. In contrast, when an Open Look window is busy, the window header (or icon, if the window is closed) turns gray. Thus, you can move the pointer out of the window and work on something else, and still tell at a glance when the window is again responsive.

Device independence

Open Look was designed specifically to be used across a wide range of hardware. This requirement means that the visuals must work well on displays of various resolutions and sizes and on both monochrome and color. It also means that all the details of the look – each graphical element and the amount of white space between elements – must be specified in device-independent terms rather than as bit maps.

Hardware differences on the input side are also significant. The number of modifier keys (e.g., Alt, Option, and Control) varies on different keyboards, as does the number of buttons on different mice. As far as possible, Open Look insulates you from such variations by allowing a great deal of flexibility in mapping mouse buttons and modifier keys to functions.

Changing horses

Design is never done in a vacuum. The user of a new interface will always approach it with a background of experience with existing interfaces. This means that every change comes at the price of increased learning effort on the part of the user.

The Open Look design team envisioned a typical user who wants to switch easily between Open Look, the Mac Finder, and the Presentation Manager. We therefore ruled out design possibilities that would make this switch too difficult.

Take the example of scroll bars. There are endless variations on the scroll bar concept, and many other possible ways to scroll that don’t even involve scroll bars. After considering many of these possibilities, we became convinced that Open Look’s scrolling mechanism had to be similar enough to what people were used to so they could use it successfully right away. The design task, then, was to refine the familiar scroll bars, making them more visually attractive and more efficient.

An Open Look at the future

Figure 6: Toolkits for the Open Look user interface will allow software developers to develop applications for a variety of windowing systems running on widely disparate hardware and operating systems. The first toolkits available will be for Unix systems.
This image can be zoomedFigure 6: Toolkits for the Open Look user interface will allow software developers to develop applications for a variety of windowing systems running on widely disparate hardware and operating systems. The first toolkits available will be for Unix systems.
The Open Look Functional Specification – a thick book addressed to the developers of user-interface toolkits and describing the look and feel in great detail – was distributed to over 1000 firms for review in July 1988 and will be published this month. (A toolkit is a set of system-specific libraries containing the standard building blocks – such as windows, menus, and scroll bars – that an application developer uses in creating an application. Figure 6 shows where a toolkit fits into the overall software architecture.)

The Open Look Application Style Guide, a somewhat thinner book addressed to application developers, gives guidelines for how to use the various building blocks that Open Look provides. The Style Guide will be published in early 1989.

Since the Functional Specification does not specify a particular hardware or software platform, it leaves room for different toolkits to implement the Open Look user interface on different systems. The first two Open Look toolkits – available in the first quarter of 1989 – will be XT+ from AT&T and View2 from Sun, both based on MIT’s X-Windows, a windowing system for Unix.

Sun is also developing an Open Look toolkit called NDE (for NeWS Development Environment) based on the NeWS window system. NeWS is a portable, PostScript-based window system that is commercially available for many platforms, including Unix, OS/2, and the Macintosh. Thus, when NDE becomes available in the second quarter of 1989, Open Look will be able to provide a common look and feel across a wide variety of computers and operating systems.

Tony Hoeber

Tony Hoeber is the leader of the Open Look design team for Sun Microsystems (Mountain View, California). He can be reached on BIX c/o “editors.”

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Page added on 25th June 2005.

Copyright © 2002-2006 Marcin Wichary, unless stated otherwise.