Editing Scrollbar (section)

{{Short description|Graphical user interface element}}
[[File:Scrolling-gedit.png|right|300px|thumb|Examples of horizontal and vertical scrollbars around a text box]]
[[File:Scrolling bar.png|right|300px|thumb| Examples of vertical scrollbar at right end of Wikipedia home page]]
A '''scrollbar''' is an [[interaction technique]] or [[widget (GUI)|widget]] in which continuous text, pictures, or any other content can be [[Scrolling|scrolled]]  in a predetermined direction (up, down, left, or right) on a [[computer display]], [[window (computing)|window]], or [[viewport]] so that all of the content can be viewed, even if only a fraction of the content can be seen on a device's screen at one time. It offers a solution to the problem of [[Web navigation|navigation]] to a known or unknown location within a two-dimensional information space.<ref>{{cite journal|last1=Beard|first1=David V.|last2=Walker II|first2=John Q.|title=Navigational techniques to improve the display of large two-dimensional spaces|journal=Behaviour & Information Technology|date=1990|volume=9|issue=6|pages=451–466|doi=10.1080/01449299008924259}}</ref> It was also known as a '''handle''' in the very first [[GUI]]s. They are present in a wide range of electronic devices including computers, graphing calculators, mobile phones, and portable media players. The user interacts with the scrollbar elements using some method of direct action, the scrollbar translates that action into scrolling commands, and the user receives feedback through a visual updating of both the scrollbar elements and the scrolled content.<ref name="lafon">{{cite book|last1=Beaudouin-Lafon|first1=Michel|title=Proceedings of the working conference on Advanced visual interfaces |chapter=Designing interaction, not interfaces |date=2004|pages=15–22|doi=10.1145/989863.989865|isbn=1581138679|s2cid=3395621}}</ref>

Although scrollbar designs differ throughout their history, they usually appear on one or two sides of the viewing area as long rectangular areas containing a bar (or thumb) that can be [[Mouse gesture|dragged]] along a trough (or track) to move the body of the document. This can be placed vertically, horizontally, or both in the window depending on which direction the content extends past its boundaries. Two arrows are often included on either end of the thumb or trough for more precise adjustments. The "thumb" has different names in different environments: on the [[Mac OS X Tiger|Mac OS X 10.4]] it is called a "scroller";<ref>[https://developer.apple.com/documentation/UserExperience/Conceptual/APStyleGuide/APSG_2008.pdf Apple Publications Style Guide 2008] {{webarchive |url=https://web.archive.org/web/20090612022848/http://developer.apple.com/documentation/UserExperience/Conceptual/APStyleGuide/APSG_2008.pdf |date=June 12, 2009 }}</ref> on the [[Java (programming language)|Java]] platform it is called "thumb" or "knob"; [[Microsoft]]'s .NET documentation refers to it as "scroll box" or "scroll thumb"; in other environments it is called "elevator", "quint", "puck", "wiper" or "grip"; in certain environments where browsers use agnostic language to the scrollbar terminology, the thumb is referred to as the 'pea' for vertical movement of the bar and still use 'puck' for horizontal movement.

Additional functions may be found, such as zooming in/out or various [[computer software|application]]-specific tools. Depending on the GUI, the size of the thumb can be fixed or variable in size; in the later case of proportional thumbs, its length would indicate the size of the window in relation to the size of the whole document, indicated by the full track. While proportional thumbs were available in several GUIs, including [[Graphics Environment Manager|GEM]], [[AmigaOS]] and [[PC/GEOS]], even in the mid 1980s, Microsoft did not implement them until [[Windows 95]]. A proportional thumb that completely fills the trough indicates that the entire document is being viewed, at which point the scrollbar may temporarily become hidden. The proportional thumb can also sometimes be adjusted by dragging its ends, such as in [[Sony Vegas]], a [[Non-linear editing|non-linear]] [[video editing software]] package. In this case it would adjust both the position and the zooming of the document, where the size of the thumb represents the degree of zooming applied.
<!-- Commented out: [[File:Copland Platinum theme.png|thumb|Non-proportional scrollbars in Mac OS from 1996, before the scrollbar length became proportional to the amount of content present.]] -->

A scrollbar should be distinguished from a ''[[slider (computing)|slider]]''  which is another visually similar yet functionally different object. The slider is used to change values, but does not change the display or move the area that is shown as a scrollbar does.