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Windows

Figure 14-36 The Delete button on the inactive window does not support click-through

In general, you can implement click-through for a command that provides confirmation feedback before executing, even if the command ultimately results in destruction of data. For example, you can provide click-through for a delete button if you make sure to provide the user with the ability to cancel or confirm the action before it executes. For example, in Accounts preferences, the button for deleting users provides click-through because it also provides a confirmation dialog before executing.

If you want to implement click-through for an item that doesn’t provide confirmation feedback, consider how difficult it will be for the user to undo the action after it’s performed. For example, in Mail, the Delete button does not provide click-through because it deletes a message without providing feedback first, which is a potentially harmful action and one that is difficult to undo. Click-through for the New button in Mail is fine because its resulting action is not harmful and is easy to undo.

Scrolling Windows

People use scroll bars to view areas of a document or a list that is larger than can fit in the current window. Only active windows can be scrolled. A window can have a horizontal scroll bar, a vertical scroll bar, both, or neither. A window that has one or more scroll bars also has a resize control in the bottom right corner. Figure 14-37 shows the parts of a scroll bar in a window.

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

C H A P T E R 1 4

Windows

Figure 14-37 The elements of a scroll bar

Scroll bar

The scroller size reflects how much of the content is visible; the smaller the scroller, the less of the content the user can see at that time. The scroller represents the relative location, in the whole document, of the portion that can be seen in the window.

If the entire contents of a document is visible in a window, the scroll bars do not contain scrollers. Scroll bars in inactive windows have an inactive appearance. In Figure 14-36 (page 220) you can see the inactive appearance in the scroll bar of the Mail viewer window.

For most document windows that contain a single view (scrolling text or tables, for example), do not specify any space between the window edge and scroll bars.

The user can use scroll bars by doing the following:

■Dragging the scroller. This method is usually the fastest way to move around a document. The window’s contents changes in “real time” as the user drags the scroller.

■Clicking a scroll arrow. This means, “Show me more of the document that’s hidden in this direction.” The scroller moves in the direction of the arrow. Each scroll arrow click moves the content one unit; your application determines what one unit equals. For example, a word processor would move a line of text per click, a spreadsheet could move one row or column. To ensure smooth scrolling effects, specify units of the same size throughout a document.

■Clicking or pressing in the scroll track. Clicking advances the document by a windowful (the default) or to the pointer’s hot spot, depending on the user’s choice in Appearance preferences. A “windowful” is the height or width of the window, minus at least one unit of overlap to maintain the user’s context.

This unit of overlap should be the same as one scroll arrow unit (for example, a line of text, a row of icons, or part of a picture). The Page Up and Page Down keys also move the document view by a windowful.

Pressing in the scroll track displays consecutive windowfuls of the document until the location of the scroller catches up to the location of the pointer (or until the user releases the mouse button).

It’s best not to add controls to the scroll-bar area of a window. If you add more than one control to this area, it’s hard for people to distinguish among controls and click the right one. Acceptable additions to the scroll area include a splitter bar and a status bar that shows, for example, the current page. To ensure that window controls are easy to use and understand, it’s best to place the majority of your features in the menus as commands. If you really want to provide additional access to features, consider creating a panel. Only frequently accessed features that significantly benefit users’ productivity should be elevated to the primary interface.

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