
2.4.4.5 Scrollbars
Scrollbars implement the OPEN LOOK metaphor of an elevator on a cable. These components
are shown in Figure 2-12.
Figure 2-12. Vertical scrollbar components
A scrollbar is an object that can exist independently or attach itself to various types of
subwindows. The scrollbar is subclassed from the WINDOW class since it is a visual object.
However, because its functionality is very tightly bound to other objects, the scrollbar is
sometimes considered to be a property of those objects.
OPENWIN subclasses (canvas and
text-based packages) require scrollbars to provide splittable views, and scrollbars can be
created automatically by such objects. Typically, it is your responsibility to pass a hint to the
object that it should create the scrollbar using the appropriate attribute-value pair. Neverthe-
less, scrollbars can be manually attached or detached to OPENWIN objects, or they can be
created independently of these objects