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| Scroll Bars |
scrollbar
is a vertical or horizontal bar on a window with a little box inside
it (called the slider or " thumb") that can be
dragged along it with the mouse. Applications use the scrollbar not
only to set the position of something (such as the text cursor in a
textbox or the currently displayed page of a word processor
document), but to give us visual feedback of where we are and how
much stuff we can't see. The thumb shows us where we
are in the entire piece of text, and the size of the thumb shows us
what percentage we're viewing. (A large thumb means
that most of what's there is visible and a small
thumb means that there's a lot we
can't see.) The scrollbar usually becomes disabled
(grayed
out) if there's no scrolling to be done.Click the up or down arrows to move the scroll bar incrementally, or
drag the thumb with the mouse to move to the desired position. You
can also click in the gray areas between the arrows and the thumb to
move up or down a page at a time.It is possible to use the cursor keys and PgUp/PgDn keys to control
the scrollbar if it has the
focus.
If the scrollbar is part of another control, such as the textbox
shown in Figure 3-22, then it cannot receive the
focus to receive keyboard input directly. Instead, use the cursor
keys to navigate in the listbox or input field with which the
scrollbar is associated. The thumb blinks if it has the focus.
Figure 3-24. Use scrollbars to view all of the items in a folder when the folder window is not sufficiently large
