LPIC-1 106.3 — Accessibility

Exam weight: 1 — LPIC-1 v5, Exam 102

What You Need to Know

From the official LPIC-1 objectives:

Basic knowledge of visual settings and themes.
Basic knowledge of assistive technology.

Key terms: High Contrast/Large Print Desktop Themes, Screen Reader, Braille Display, Screen Magnifier, On-Screen Keyboard, Sticky/Repeat keys, Slow/Bounce/Toggle keys, Mouse keys, Gestures, Voice recognition.

Accessibility Settings

The Linux desktop provides settings and tools to adapt the user interface for people with disabilities. The standard interface devices — screen, keyboard, and mouse/touchpad — can each be reconfigured to overcome visual impairments or reduced mobility.

Accessibility settings are found in the system configuration panel:

Desktop	Location
GNOME	Universal Access
KDE	System Settings → Personalization → Accessibility
Xfce	Accessibility (reduced feature set compared to GNOME/KDE)

GNOME can be configured to permanently show the Universal Access menu in the top-right corner of the screen for quick switching. The visual bell feature (called visual bell in KDE) replaces sound alerts with a visual cue — useful for users with hearing impairments.

Keyboard and Mouse Assist

Sticky Keys

Allows typing keyboard shortcuts one key at a time. When enabled, combinations like Ctrl+C do not need to be held simultaneously — press Ctrl, release it, then press C.

GNOME: Typing Assist section of Universal Access.
KDE: Modifier Keys tab of Accessibility. KDE also offers Locking Keys — Alt, Ctrl, Shift stay “down” if pressed twice (like Caps Lock).

Bounce Keys

Inhibits unintended key presses by placing a delay between them. A new key press is accepted only after a specified time has passed since the last one. Useful for users with hand tremors.

GNOME: applies only to repeated same-key presses.
KDE: applies to any key press; found in the Keyboard Filters tab.

Slow Keys

Requires the user to hold down a key for a specified time before it is accepted, preventing accidental keystrokes.

Activation Gestures

Sticky Keys and Slow Keys can be toggled on/off via keyboard gestures:

Sticky Keys: press Shift five consecutive times.
Slow Keys: hold Shift for eight consecutive seconds.

In KDE, the option is called Use gestures for activating sticky keys and slow keys. In GNOME it is called Enable by Keyboard in the Typing Assist window.

AccessX and xkbset

Sticky keys, Bounce keys, Slow keys, and Mouse Keys are accessibility features provided by AccessX, a resource within the X Keyboard Extension (XKB). AccessX settings can also be modified from the command line with the xkbset command.

Mouse Keys

Allows controlling the mouse pointer with the numerical keypad:

2 — move down, 4 — move left, 7 — move northwest, etc.
5 — left mouse click (default).
GNOME: a single switch in Universal Access.
KDE: System Settings → Mouse → Keyboard Navigation; speed and acceleration can be customized.

Screen Keyboard

When physical keyboard usage is impossible or uncomfortable, an on-screen keyboard can be used:

GNOME: Screen Keyboard switch in Universal Access — appears whenever the cursor is in a text field.
KDE and others: the onboard package provides a simple on-screen keyboard for any desktop environment.

Mouse Click Assist

If clicking or dragging causes pain or is impractical:

GNOME Click Assist:
- Simulate a right mouse click — hold left button to generate a right-click.
- Simulate clicking by hovering — click triggered when mouse stays still.
KDE: KMouseTool application provides the same features.

Visual Impairments

High Contrast Theme

Makes windows and buttons easier to see by drawing them in sharper colors. Available in GNOME’s Seeing section of Universal Access and in most other desktop environments’ appearance settings.

Large Text

Enlarges the standard screen font size.

Cursor Size

Allows choosing a bigger mouse cursor to make it easier to locate on the screen.

Screen Magnifier

For users who need to zoom in on parts of the screen:

GNOME: Zoom in Universal Access — configurable magnification ratio, magnifier position, and color adjustments.
KDE: KMagnifier application (available via the application launcher).
Xfce: zooms in and out by rotating the mouse scroll wheel while Alt is held.

For users who cannot use the graphical interface visually, a screen reader generates a synthesized voice to report screen events and read the text under the mouse cursor.

The most popular screen reader for Linux is Orca, usually installed by default. Orca also works with refreshable braille displays — special devices that display braille characters by raising small pins felt with the fingertips.

Quick Reference

Keyboard accessibility features (AccessX / XKB):
  Sticky Keys    type shortcuts one key at a time (Ctrl, then C)
  Bounce Keys    delay between presses; rejects rapid repeats (hand tremors)
  Slow Keys      must hold key for set time before it registers
  Mouse Keys     control mouse pointer with numpad (5 = left click)

Activation Gestures (toggle via keyboard):
  Sticky Keys    press Shift 5 times in a row
  Slow Keys      hold Shift for 8 seconds

Command-line AccessX control:
  xkbset         modify AccessX settings from the terminal

On-screen keyboard:
  GNOME          Screen Keyboard switch in Universal Access
  KDE/others     onboard package

Visual accessibility:
  High Contrast    sharper colors for windows and buttons
  Large Text       enlarged font size
  Cursor Size      bigger mouse cursor
  Zoom (GNOME)     screen magnifier — configurable ratio, position, colors
  KMagnifier       KDE screen magnifier application
  Orca             screen reader — synthesized voice + refreshable braille display support

Accessibility settings location:
  GNOME    Universal Access
  KDE      System Settings → Personalization → Accessibility
  Xfce     Accessibility (reduced feature set)

Exam Questions

What accessibility feature allows typing key combinations one key at a time? → Sticky Keys
What does Bounce Keys do? → Adds a delay between key presses so rapid accidental repeats (e.g. from hand tremors) are rejected.
What does Slow Keys do? → Requires the key to be held for a set time before it is accepted.
What is the keyboard gesture to enable Sticky Keys? → Press Shift five consecutive times.
What is the keyboard gesture to enable Slow Keys? → Hold Shift for eight seconds.
What command-line tool modifies AccessX settings? → xkbset
What extension of the X Window System provides Sticky, Bounce, Slow, and Mouse Keys? → AccessX (within XKB — X Keyboard Extension)
How does Mouse Keys work? → The numerical keypad controls the mouse pointer; 5 = left click by default.
What package provides an on-screen keyboard for any desktop environment? → onboard
In GNOME, where are accessibility settings found? → Universal Access
In KDE, where are accessibility settings found? → System Settings → Personalization → Accessibility
What GNOME feature replaces sound alerts with visual cues? → Visual bell (visual alert)
What does High Contrast do? → Draws windows and buttons in sharper colors to improve visibility.
What GNOME screen magnifier feature is called? → Zoom (in Universal Access)
What KDE screen magnification application is available? → KMagnifier
What is the most popular screen reader for Linux? → Orca
What additional device does Orca support besides the screen? → Refreshable braille displays
What KDE application assists mouse clicks by clicking when the cursor pauses? → KMouseTool

Exercises

Exercise 1 — Sticky Keys for Alt+Tab

What accessibility feature could help a user to alternate between open windows using the keyboard, considering that the user is unable to press Alt and Tab at the same time?

Answer

Sticky Keys — allows pressing keyboard shortcuts one key at a time. The user can press Alt, release it, then press Tab without holding both simultaneously.

Exercise 2 — Bounce Keys and Hand Tremors

How could the Bounce Keys accessibility feature help users whose involuntary hand tremors disturb their typing?

Answer

Bounce Keys places a delay between accepted key presses. A new key press is accepted only after a specified time has passed since the last one. Tremor-induced accidental rapid repeats of the same key are therefore rejected, reducing unwanted characters in typed text.

Exercise 3 — Activation Gesture for Sticky Keys

What is the most common Activation Gesture for the Sticky Keys accessibility feature?

Answer

Pressing the Shift key five consecutive times activates Sticky Keys (when Activation Gestures are enabled). To activate Slow Keys, hold Shift for eight consecutive seconds.

Exercise 4 — KDE Mouse Click Assist

In KDE, what application helps users with repetitive strain injuries by automatically clicking the mouse whenever the cursor pauses briefly?

Answer

KMouseTool — it monitors the mouse cursor position and simulates a click when the cursor remains still for a set interval, reducing the need to physically click the mouse button.

Exercise 5 — Visual Adjustments for Readability

What appearance aspects of the graphical environment can be modified to make it easier for people to read text on the screen?

Answer

High Contrast theme — sharper color distinction between interface elements.
Large Text — enlarges the standard screen font size.
Cursor Size — bigger cursor is easier to locate.
Screen Magnifier (Zoom in GNOME, KMagnifier in KDE) — zooms into any part of the screen with configurable magnification ratio.

LPIC-1 Study Notes | Topic 106: User Interfaces and Desktops