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Keyboard Access
ISSUE:
A user with a disability may be unable to use a mouse or similar pointing device — relying solely on the keyboard for navigation. A user with a mobility impairment may not possess the fine motor-control required for precision mouse movements. A user who is blind cannot visually target the mouse pointer. Providing keyboard equivalents for all mouse actions (e.g., access to menus, toolbars, buttons and links) is essential in accommodating users with disabilities.
Accessibility options within the operating system can make it possible for users with a variety of disabilities to access a computer. Accessibility Options are available from the Windows Control Panel and are part of the AccessX package on Unix systems. If application software interferes with these accessibility features, system and application access for users with disabilities may be lost.
| FEATURE | DESCRIPTION | IMPLEMENTATION |
|---|---|---|
| STICKYKEYS | Allows a user To sequentially press and release each individual key in a multiple-key function/command (e.g., ctrl+p or ctrl+alt+delete). | Windows and CDE/Motif systems: press the Shift key 5 times. |
| FILTERKEYS | Allows users to slow the keyboard repeat rate. CDE/Motif systems provide similar support through the "SlowKeys" and "RepeatKeys" features. |
Windows : hold down the right Shift key for 8 seconds. CDE/Motif systems : hold down either Shift key for 8 seconds. |
| TOGGLEKEYS | Allows users to hear tones when the Caps lock, Num Lock or Scroll Lock Keys are pressed. | Windows: hold down the Num Lock key for 5 seconds. CDE/Motif systems: provide a ToggleKeys function but no keyboard shortcut for enabling/disabling it. |
| HIGH CONTRAST | Allows users to set the default system color and font scheme to one that is easier for them to read. | Windows: press Left-Alt key+Left-Shift key+PrintScreen key. CDE/Motif systems: feature not available. |
| MOUSEKEYS | Allows users to move the mouse pointer using the arrow keys on the keyboard. | Windows: press Left-Alt key+Left-Shift key+Num Lock key. CDE/Motif systems: provide a MouseKeys function but no keyboard shortcut for enabling/disabling it. |
- CDE/Motif systems also reserve the following key sequences:
- 6 consecutive clicks of Ctrl for enabling/disabling screen-reader numeric keypad functions.
6 consecutive clicks of Alt reserved for future AccessX use.
STANDARD:
- Key combinations used within an application shall
- be consistent throughout the application;
- adhere to standard operating system conventions;
- not conflict with operating system accessibility features/keystrokes.
- Only Shift, Alt, and Control shall be used as application defined accelerator/modifier keys.
- Standard keyboard navigation functionality shall be maintained.
| KEYSTROKE | ACTION |
|---|---|
| TAB | Move focus forward through the active regions of a dialog. |
| SHIFT+TAB | Move focus backward through the active regions of a dialog. |
| ARROW KEYS | Select an option in a control group. |
| ENTER | Activate a control. |
| F6 | Move focus between Window panels. |
| CTRL+TAB | Move focus forward, from tab to tab, in a multi-tab dialog. |
| CTRL+SHIFT+TAB | Move focus backward, from tab to tab, in a multi-tab dialog. |
Windows applications that hides some keyboard user interface elements or disable some keyboard mechanisms by default should enable them when the Keyboard Preference flag is set (Control Panel Accessibility Options/Keyboard/Show extra keyboard help in programs).
Programmer's Note: An application tests for this flag by calling the SystemParametersInfo function with the SPI_GETKEYBOARDPREF value.
