Scrollbar

They are present in a wide range of electronic devices including computers, graphing calculators, mobile phones, and portable media players.

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 video editing software package.

In 1974, moving the cursor to the left margin while using Bravo changed its shape to a double-headed arrow to allow for scrolling.

Holding down the middle yellow button changed the cursor to a thumb, allowing for jumping to that percentage of the document with an indicator of current placement.

Upon pressing the thumb, dragging it would bring it to that particular point unless movement was made far out of the scrollbar before release, aborting the action.

GEM allowed the mouse to be moved far away from the scrollbar after clicking and holding, to reduce hand-eye coordination problems.

In 1997, the PalmPilot included a conventional scrollbar where text extended past screen boundaries with use of both a draggable thumb and arrows that could be tapped with a stylus.

In 2007, the iPhone and iOS included a regular scrollbar in the web browser and other applications, though it was only for output and could not be interacted with.

[12] In 2011, Mac OS X 10.7 removed the buttons from the end of the bar and was designed to look more like the iOS scrollbar.

The placement within a document was no longer visible when the mouse was outside the bar area even if the window in question was in focus.

The trough above or below the thumb can be clicked in order to immediately jump to that point on the page, or page-by-page for multipage content.

[15] After clicking the trough, scrolling automatically begins and then stop once the thumb has reached the position of the mouse pointer.

Many applications, such as Microsoft Word and PowerPoint, contain scrollbars with on screen directional arrows for purposes of scrolling.

[15] Sometimes, both arrow buttons appear next to each other for quick, precise manipulation without having to drag the thumb or move the mouse great distances to the other arrow (this was offered as an option in Mac OS 8.5); one of them may also be duplicated so as to show at both ends of the bar, providing familiarity for those used to both separate and adjacent buttons.

These arrow buttons existed until Mac OS X 10.7 where they were dropped in favor of trackpad gestures and scroll-wheel mice.

Similarly, the scrollbar can be directly placed within the content where it is useful, both decreasing space used and reducing required pointer movements.

[20] This can be a blank field to signal a list's end, disabling of scrolling buttons, and color changes in the scrollbar.

Special scroll-bar like graphical control elements allow panning around a two-dimensional space by simply moving a single rectangle in any direction on the plane.

Many GUI operations in RISC OS perform a related but slightly different function when right clicked.

[23][24] And in WebKit-based browsers, there are pseudo-elements called: WebKit also provides many pseudo-classes to modify the style of scrollbars.

[26] For example, Google Chrome introduces trough marks in the vertical scrollbar to indicate places in the document where a particular search term was found.

Computer literate users are often familiar with scrollbars, but those with limited knowledge may not intuitively understand them, especially given more recent variations, without assistance.

In terms of design, if the window size is already small, the visible content area will be further reduced by the presence of a scrollbar.

[20] While some more recent disappearing scrollbars help mitigate this problem, more traditional ones do not avoid it, especially when there are both horizontal and vertical bars present.

[29] Overshooting can also occur when attempting to position near the top or the bottom of a single page within a larger set.

[15] A 1986 report by William Buxton and Brad Myers tested different two-handed interactions, including scrolling, clicking, and resizing.