C H A P T E R 8

User Input

If no text is selected, the extension begins at the insertion point. If text is selected by dragging, then the extension begins at the selection boundary. For example, in the phrase stop time, if the user places the insertion point between the “s” and “t” and then presses Shift–Option–Right Arrow, top is selected. However, if the user double-clicks so the whole word is selected, and then extends the selection left or up, it’s as if the insertion point were before the “s.” If the user extends the selection right or down, it’s as if the insertion point were between the “p” and the space after the word.

Reversing the direction of the selection deselects the appropriate unit. In the previous example, if the word stop is selected and the user presses Shift–Option–Right Arrow, so stop time is selected, and then presses Shift–Option–Left Arrow, time is deselected and stop remains selected.

Moving the Insertion Point in “Empty” Documents

Varioustext-editingprogramstreatemptydocumentsindifferentways. Someassumethatanemptydocument contains no characters, in which case clicking at the bottom of a blank window 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 window 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 15 nondedicated function keys on desktop Macintosh keyboards (F1 through F15). 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. For example, portable computers usually have 12 nondedicated function keys (F1 through F12), not 15 and don’t have Help keys or Forward Delete keys.

Help

Pressing the Help key may invoke the application’s help in Help Viewer. The key combination Command-Shift-/ (sometimes shortened to Command-?) should always display the application’s help in Help Viewer.

Forward Delete (Fwd Del)

Pressing the Forward Delete (labeled Del) 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 Fwd Del is pressed, it has the same effect as pressing Delete (Backspace) or choosing Delete from the Edit menu.

You can support Option–Fwd Del to delete the next larger semantic unit, as described in “Moving the Insertion Point” (page 100) 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.

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