scroll bar

[′skrōl ‚bär] (computer science) A horizontal or vertical bar that contains a box that is clicked and dragged up, down, left, or right in order to scroll the screen.

scroll bar

(graphics)A widget found in graphical user interfaces andused to show and control ("scroll") which portion of adocument is currently visible in a window. A window may havea horizontal or, most often, vertical scroll bar or both.

A vertical scroll bar is a narrow strip drawn up the side ofthe window containing a "bubble" whose position in the scrollbar represents the position of the visible part within thewhole document. By dragging the bubble with the mouse theuser can scroll the view over the entire document. Arrowbuttons are usually provided at the end(s) of the scroll barto allow the window to be scrolled by a small amount, e.g. oneline of text, in either direction by clicking them with themouse. Some programs provide a second pair of buttons forscrolling a page at a time or some other unit. Clicking onthe scroll bar outside the bubble will either, depending onthe particular WIMP, move the bubble to that point or moveit some amount (typically a screenful) in that direction.

Different WIMP systems define different standards forwhether scroll bars appear on the left or right, top or bottomof the window, and for their behaviour.

To reduce mouse movement, the up and down scroll buttonsshould either be next to each other at one end of the scrollbar (as in NEXTSTEP) or should reverse their effect whenclicked with the right-hand mouse button (as in the X Window System and RISC OS). The fraction of the scroll bar filledby the bubble should indicate the fraction of the documentvisible in the window.

scroll bar

A vertical bar on the right side of a window or a horizontal bar at the bottom of a window that is used to move the window contents up and down or left and right. The bar contains a "thumb", which looks like an elevator in a shaft. When dragged with the mouse, the window contents move correspondingly. When the bar is clicked above or below the thumb, the contents are moved a page at a time. The arrows are clicked to move one line at a time.

Becoming Somewhat Obsolete
Since the advent of scroll mice, which use a wheel for vertical and horizontal scrolling, the scroll bar is being used less and less on desktop applications. In addition, tablet and smartphone content is scrolled by fingers, and a scroll bar was never a natural part of the interface. See scroll mouse.

Scroll Bars

Clicking in the bar or dragging the thumb moves the contents within the window. The Mac example (right) shows an optional variation that places both scroll arrows in the same vicinity to lessen mouse movement when switching directions.