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■Choosing Close from the File menu

■Pressing Command-W

■Clicking the close button

When a user closes a document window, your application should:

■Decide what to do with unsaved data (see “Dialogs for Saving, Closing, and Quitting” (page 241))

■Store the window’s onscreen position and size (so they can be used when the window is reopened)

In most cases, applications that are not document-based should quit when the main window is closed. For Example, System Preferences quits if the user closes the window. If an application continues to perform some function when the main window is closed, however, it may be appropriate to leave it running when the main window is closed. For example, iTunes continues to play when the user closes the main window.

Window Layering

Each application and document window exists in its own layer, so documents from different applications can be interleaved. Clicking a window to bring it to the front doesn’t disturb the layering order of any other window.

A window’s depth in the layers is determined by when the window was last accessed. When a user clicks an inactive document or chooses it from the Window menu, only that document, and any open panels, should be brought to the front. Users can bring all windows of an application forward by clicking its icon in the Dock or by choosing Bring All to Front in the application’s Window menu. These actions should bring forward all of the application’s open windows, maintaining their onscreen location, size, and layering order within the application. For more information, see “The Window Menu” (page 182).

Panels are always in the same layer, the top layer. They are visible only when their application is active and they float on top of any document windows in the application.

Users can cycle forward or backward through all open document windows by using Command-Grave Accent (Command-`) and Command-Shift-Grave Accent (Command-Shift-`). If full keyboard access is on, they can cycle through all windows by using Control-F4 and Shift-Control-F4.

Main, Key, and Inactive Windows

Windows have different looks based on how the user is interacting with them. The foremost document or application window that is the focus of the user’s attention is referred to as the main window. The main window is often also the key window. The key window is the window that accepts user input, whether from the keyboard, mouse, or alternative input device. The “close window” keyboard shortcut, Command-W, targets the key window.

However, the main window is not always the key window. There are times when a window other than the main window takes the focus of the input device, while the main window still remains the focus of the user’s attention. For example, when a person is using an inspector, a Find dialog, or the Fonts or Colors windows, the document is the main window and the other window is the key window.

If the main and key window are different windows, they are distinguished from one another by the look of their title bars (and toolbars, if they are present). In particular, note that the key window displays title-bar controls with color.

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

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Main and key windows are both active windows. An active window is visually distinct from an inactive window in that its title bar (and its toolbar, if there is one) displays the standard window-frame color, while the title bar (and toolbar) of an inactive window displays a lighter shade of the window-frame color. Inactive windows are windows the user has open, but that are not in the foreground. Main and key windows are always in the foreground, but only the controls of the key window have color. An active window that is not key has active, but clear, controls.

Note: A transparent panel that is key displays a subtly reflective title bar and a white title, whereas a non-key transparent panel displays a darker title bar and a light gray title. See “Transparent Panels” (page 225) for more information about transparent panels.

The visual distinctions between main, key, and inactive windows are shown in Figure 14-34.

Figure 14-34 Main, key, and inactive windows

Inactive window

Main window

Key window

Click-Through

An item that provides click-through is one that a user can activate on an inactive window with one click, instead of clicking first to make the window active and then clicking the item. Click-through provides greater efficiency in performing such tasks as closing or resizing inactive windows, and copying or moving files. In many cases, however, click-through could confuse a user who clicks an item unintentionally.

Click-through is not a property of a class of controls. Any control, including toolbar items, can support click-through in many contexts, but the same control could disable click-through when its use could be destructive or difficult to reverse in a particular context.

In an inactive window, items that do not provide click-through should appear in their disabled state. Figure 14-35 shows controls that do support click-through in an inactive window.

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

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Figure 14-35 An inactive window with controls that support click-through

All the controls in this window support click-through.

In a single window, you can provide click-through for any subset of items; you do not have to choose between supporting click-through for all items or none. Examine the controls in your window to see which items a user might want to activate while the window is inactive. Use the following guidelines to help you determine which items should not support click-through.

Don’t provide click-through for an item or action that:

■Is potentially harmful and does not allow the user to cancel it (for example, the Delete button in Mail)

■Is difficult or impossible to cancel (such as the Send button in Mail)

■Dismisses a dialog without telling the user what action was taken (for example, the Save button in a Save dialog that overwrites an existing file and automatically dismisses the dialog)

■Removes the user from the current context (for example, selecting a new item in a Finder column can change the target of the Finder window)

Clicking in any one of these situations should result in the containing window being brought forward, but no action being taken. Figure 14-36 shows an example of a control that does not support click-through, because its action is destructive.

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