C H A P T E R 8

User Input

Double-clicking is most commonly used as a shortcut for other actions, such as pressing Command-O to open a document or dragging to select a word. Because not everyone is physically able to perform a double click, it should never be the only way to perform an action.

Some applications support triple-clicking. For example, in a word processor, the first click sets the insertion point, the second click selects the whole word, and the third click selects the whole sentence or paragraph. Supporting more than three clicks is inadvisable.

Pressing and Holding

Pressing means holding down the mouse button while the mouse remains stationary. Pressing by itself should have no more effect than clicking does, except in well-defined areas such as scroll arrows, where it has the same effect as repeated clicking, or in a Dock tile, where it displays a menu. For example, pressing a Finder icon should select the icon but not open it.

Dragging

Dragging means pressing the mouse button, moving the mouse to a new position, and releasing the mouse button. The uses of dragging include selecting blocks of text, choosing a menu item, selecting a range of objects, moving an icon from one place to another, and shrinking or expanding an object.

Dragging a graphic object should move the entire object (or a transparent representation of it), not just the object’s outline.

Your application can restrict an object from being moved past certain boundaries, such as the edge of a window. If the user drags an object and releases the mouse button outside the boundary, the object stays in the original location. If the user drags the item out of the boundary and then back in before releasing the mouse button, the object moves to the new location. Your application can also automatically scroll a document if the user moves an object beyond the boundary of a window (see “Automatic Scrolling” (page 222)).

If the user drags a proxy object to an area that would cause that proxy object to disappear, display the poof cursor to indicate that the proxy object will disappear if dragged to that location.

If the user selects an item and begins a drag but releases the item after having moved it three or fewer pixels, the item does not move.

See “Drag and Drop” (page 117) for more information about dragging and automatic scrolling.

The Keyboard

The keyboard’s primary use is to enter text. The keyboard may also be used for navigation, but it should always be an alternative to using the mouse. For more information about using the keyboard instead of the mouse, see “Keyboard Focus and Navigation” (page 107)

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