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Table 9-2 Extending text selection with the Shift and arrow keys (continued)

Moving the Insertion Point in “Empty” Documents

Various text-editing programs treat empty documents in different ways. Some assume that an empty document contains no characters, in which case clicking at the bottom of a blank screen causes the insertion point to appear at the top. In this situation, Down Arrow cannot move the insertion point into the blank space because there are no characters there.

Other applications treat an empty document as a page of space characters, in which case clicking at the bottom of a blank screen puts the insertion point where the user has clicked and lets the user type characters there, overwriting the spaces.

Whichever of these methods you choose for your application, it’s essential that you be consistent throughout.

Function Keys

There are fifteen nondedicated function keys on desktop Macintosh keyboards (F1 through F15). Default function key combinations are listed in Table 9-6 (page 178). Desktop Macintosh keyboards provide the following six dedicated function keys with standard behaviors. Because not all Macintosh computers have all function keys, don’t rely on these keys for critical keyboard shortcuts.

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Help

Pressing the Help key (or Command-? or Command-/) invokes the application’s help, if it’s available. If a help system isn’t available, the Help key should at least display some sort of helpful screen.

Forward Delete (Del)

Pressing this key deletes the character after the insertion point, shifting everything following the removed character one position back. The effect is that the insertion point remains stationary while it “vacuums” the character or selection ahead of it.

If something is selected when Del is pressed, it has the same effect as pressing Delete (Backspace) or choosing Delete from the Edit menu.

You can support Option-Del to delete the next larger semantic unit, as described in “Moving the Insertion Point” (page 171), but deleting more than one word at a time is inadvisable. Users prefer to select large amounts of text with the mouse so they have more control over what they’re deleting.

Home, End

Pressing the Home key is equivalent to moving the scrollers all the way to the top and to the left. In a text document, for example, pressing Home scrolls to the beginning of the document; in a spreadsheet, it may scroll to the beginning of the spreadsheet or to the beginning of a row. These keys should also work in scrolling lists to display the top or bottom of the list.

End is the opposite of Home: It scrolls to the end of a document.

If the beginning or end of the document is already reached, pressing Home or End produces a system alert sound. Pressing the Home or End key has no effect on the location of the insertion point or selected data.

Page Up, Page Down

Pressing Page Up or Page Down scrolls the document up or down one page (the equivalent of clicking in the gray area of the scroll bar). If an entire page can’t be displayed in the window, these keys first scroll incrementally up or down, until the top or bottom of the page is visible, before scrolling to the next page. These keys should also work in scrolling lists.

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If the beginning or end of the document is reached, pressing Page Up or Page Down produces a system alert sound. Pressing the Page Up or Page Down key has no effect on the location of the insertion point or selected data.

Reserved and Recommended

Keyboard Equivalents

Mac OS X reserves certain keys and keyboard combinations for use by the system. These combinations, listed in Table 9-3 through Table 9-6, affect all applications and should not be used for any other function. To maintain a consistent and familiar user experience across applications, the keyboard equivalents listed in all other tables in this document are strongly recommended.

Key Combinations Reserved by the System

Don’t use these keys and combinations for actions other than those specified below.

Table 9-3 Keyboard equivalents reserved by the operating system

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Table 9-4 shows several key combinations that are reserved for use with localized versions of system software, localized keyboards, keyboard layouts, and input methods. These key combinations don’t correspond directly to menu commands.

Table 9-4 Key combinations reserved for international systems

Mac OS X (version 10.2 and later) provides a way for users to enlarge onscreen objects. Users can turn on the screen-zooming feature in the Seeing pane of Universal Access preferences. If your application uses any of the keyboard combinations in Table 9-5, they are overridden when zooming is turned on.

Table 9-5 Key combinations used with screen zooming

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Mac OS X 10.1 and later provides the option of full keyboard access mode, in which users can navigate through windows and dialogs. (See “Full Keyboard Access Mode” (page 184).)

Important

Your application should not override the implementation of keyboard focus and navigation in Mac OS X. These features provide functionality for users with special needs.

* Users can change these default combinations in the Full Keyboard Access pane of Keyboard preferences. When full keyboard access is on, user-defined combinations override any combinations used in applications.

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