Persons unable to use a keyboard and mouse sometimes use alternative devices. However, many users can be accomodated programatically through software that causes a standard keyboard to behave differently. Many of these features and behaviors have long been available in the XKB specification. The Open A11y Keyboard Accessibility SIG exists to identify and adopt a subset of the XKB specification in order to provide standard keyboard features and behaviors required by persons with mobility impairments.
Sticky Keys is one keyboard accessibility feature provided in the XKB specification. It supports users who cannot press key combinations. For example, the user is unable to press the Ctrl-Alt-TAB keys simultaneously, Sticky keys allows users to achieve the same result by pressing the keys sequentially.
Individuals with mobility impairments will benefit by having such features built-in and available through standard activation strategies, such as tapping the Shift key five times to activate Sticky Keys. The routines provided by the API will also benefit assistive technologies such as on screen keyboard and screen reader applications.