C H A P T E R 1 4

Windows

Bottom Bars

A bottom bar is a window-frame area that is below the window body. Bottom bars give users access to controls that directly affect the contents or organization of the window body.

In general, controls in a bottom bar are frequently used, but are somewhat less important than controls in a toolbar. For example, the bottom-bar controls in iChat allow users to add buddies to the list and to text message, call, or video chat with a selected buddy, whereas the controls in the toolbar are focused on the user of the application. Figure 14-25 shows the iChat bottom bar.

Figure 14-25 A bottom bar contains controls that affect the window-body contents or organization

Bottom Bar Appearance and Behavior

Because a bottom bar is part of the window frame, it has the same gray gradient surface that is visible in the toolbar–title bar area.

Bottom bars can contain either regular-size or small rectangular-style toolbar controls; bottom bars should not contain icon buttons, capsule-style toolbar controls, custom controls, or any standard Aqua controls. See “Controls for Toolbars and Bottom Bars” (page 250) for more information about controls that are suitable for use in a bottom bar.

Important: If you choose to use system-provided images in your bottom-bar controls, be sure to avoid redefining their meanings. For example, use the Quick Look symbol to mean "preview with Quick Look” only; don’t use it to mean “magnify.“

At the top of Figure 14-26 you can see the Address Book bottom bar (which uses small controls) and below it you can see the iCal bottom bar (which uses regular-size controls).

Window Elements

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2008-06-09 | © 1992, 2001-2003, 2008 Apple Inc. All Rights Reserved.

C H A P T E R 1 4

Windows

Figure 14-26 A bottom bar and its controls can be regular-size or small

A bottom bar with small-size controls

A bottom bar with regular-size controls

Designing a Bottom Bar

Because of its subordinate position at the bottom edge of the window, a bottom bar should not contain controls for the most frequently used commands. After all, users don’t typically look at the bottom area of a window more often than they look at the top area, so placing the most important controls at the bottom makes them harder to find. However, although items in a bottom bar are less frequently used than items in a toolbar, you should still take care to choose items that give users an easy way to perform common tasks.

Unlike toolbars, bottom bars are not user-customizable, so it’s especially important to provide a set of useful controls that is neither too general nor too specific. To help you determine which commands will be the most useful in the bottom bar of your window, be sure you understand the user’s mental model of the tasks users perform with your application. To learn more about this concept, see “Reflect the User’s Mental Model” (page 39).

After you’ve decided what commands you want to provide in a bottom bar, you need to choose or create simple, streamlined icons that are easily recognized as metaphors for these tasks. (Note that you can also use a text label in a bottom-bar control, such as “Edit.“) If possible, you should use the system-provided images (described in “System-Provided Images” (page 151)) because users are already familiar with their meanings. If you must design an icon for a bottom-bar control, try to imitate the clean lines of the system-provided images, as iCal does for its to-do bottom-bar control, shown in Figure 14-27. (For more information on designing icons for use in bottom-bar controls, see “Designing Icons for Rectangular-Style Toolbar Controls” (page 150).)

208	Window Elements

2008-06-09 | © 1992, 2001-2003, 2008 Apple Inc. All Rights Reserved.