Keyboard Interaction

Keyboard Navigation

A well-designed keyboard user interface plays a key role when you are designing applications. Many power-users prefer to perform most operations with the keyboard rather than the mouse. Visually-impaired users can navigate software more effectively using the keyboard, because using the mouse depends on visual feedback of the mouse pointer location. And mobility impairments can prevent a user from successfully navigating using the mouse, because of the fine motor control skills required.

Make all mouse actions available from the keyboard, and include keyboard access to all toolbars, menus, links and buttons. Every function your application provides must be available using the keyboard alone. Hiding your mouse while you test your application is a great way to test this!

Figure 10.4. Dialog and menu, with some of their access and shortcut keys indicated

Screenshot of a dialog and a menu with some of their access keys and shortcut keys highlighted

Most functionality is easy to make available from the keyboard, by using access keys and shortcut keys, and the toolkit's built-in keyboard navigation features. All controls with labels should have access keys, and frequently-used menu items should be assigned shortcut keys. However, operations that rely on drag-and-drop, for example, may require more thought to make them keyboard accessible.

Guidelines

  • Provide efficient keyboard access to all application features. In particular, ensure every control on menus and in dialogs are directly focusable using access keys or shortcut keys.

  • Use a logical keyboard navigation order. When navigating around a window with the Tab key, keyboard focus should move between controls in a predictable order. In Western locales, this is normally left to right and top to bottom.

  • Ensure correct tab order for controls whose enabled state is dependent on check box, radio button or toggle button state. When such a button is selected, all its dependent controls should be enabled, and all the dependent controls of any other button in the group should be disabled. When the user selects a check box, radio button or toggle button that has dependent controls, do not automatically give focus to the first dependent control, but instead leave the focus on the button.

  • Do not over-ride existing system-level accessibility features. For example, the MouseKeys feature in the GNOME Keyboard Accessibility preferences dialog allows mouse movement and button clicks to be simulated using the keypad. Therefore you cannot add features to your application that can only be accessed by pressing keys on the keypad, as users relying on the MouseKeys feature will not be able to use them.

  • Ensure that any text that can be selected with the mouse can also be selected with the keyboard. This is a convenience for all users, but especially for those for whom fine control of the mouse is difficult.

  • Ensure that objects that can be resized or moved by drag and drop can also be resized or moved with the keyboard. For example, icons and windows on the desktop. Where precision sizing and placement is potentially important, e.g. shapes in a diagram, also consider providing a dialog into which you can type co-ordinates, or a means of snapping objects to a user-definable grid.

  • Do not use general navigation functions to trigger operations. For example, do not use basic Tab keyboard navigation in a dialog to activate any actions associated with a control.

  • Show keyboard-invoked menus, windows and tooltips near the object they relate to, but without hiding or obscuring the object to which the menu or tooltip refers,. In GNOME, popup menus are activated with Shift-F10, and tooltips with Ctrl-F1.

  • Provide more than one method to perform keyboard tasks where possible. Users may find some keys and key combinations easier to use than others.

  • Do not assign awkward reaches to frequently performed keyboard operations. Some people may only be able to use one hand on the keyboard, so shortcuts that can be easily used with one hand are preferable for common operations. In any case, having to frequently perform long or difficult reaches on the keyboard can increase muscle strain for all users, increasing the risk of pain or injury.

  • Do not require repetitive use of simultaneous keypresses. Some users are only able to press and hold one key at a time. Assistive technologies such as the GNOME Keyboard Accessibility preferences dialog do allow users to press the keys sequentially rather than simultaneously, but this of course means the operation will take longer for them.

The point about not having Tab initiate any actions effectively rules out tab completion in dialogs, should we consider/recommend a "hands-free" auto-completion method instead, as offered by OpenOffice.org, Explorer etc.? What does our new 2.0 file selection dialog do?

Choosing Access Keys

Give all labelled components an access key (underlined letter), with the exception of toolbar controls which would use up too many access key combinations.

Choose access keys to be as easy to remember as possible. Normally, this means using the first letter of the label. However, in complex windows, the choice can become more difficult. Here are some simple rules:

  1. Assign access keys to the most frequently-used controls first. If it's not clear which controls will be the most frequently used, assign access keys from left to right, top to bottom (for Western locales).

  2. Use the first letter of the label, or of one of its other words if it has more than one. If another letter provides a better association (e.g. "x" in Extra Large) however, consider using that letter instead.

  3. If the first letter is not available, choose an easy to remember consonant from the label, for example, "p" in Replace.

  4. If no such consonants are available, choose any available vowel from the label.

If duplication of access keys in a window is unavoidable, you should still refrain from duplicating the access keys for any of these buttons that appear in the same window: OK, Cancel, Close, Apply or Help.

Also, it is better not to assign access keys to "thin" letters (such as lowercase i or l), or letters with descenders (such as lowercase g or y) unless it is unavoidable. The underline does not show up very well on those characters in some fonts.

Applications using a non-Roman writing system in conjunction with a standard keyboard can have control labels prefixed with Roman characters as access keys.

Choosing Shortcut Keys

The tables in the section called “Standard Application Shortcut Keys” summarize the standard shortcut keys to use when your application supports those functions. Your application will not necessarily support all of these functions, see the section called “Standard Menus” for more information. However, use the recommended shortcut keys for those functions you do support.

You will probably want to add your own shortcut keys for functions specific to your application. If so, as well as following the guidelines below, look at any other existing similar applications to see which shortcut keys they have defined. Your users may already be using those or similar applications, so being consistent where it is possible and sensible to do so will provide a better user experience for them when they begin to use yours.

Guidelines

  • Use Ctrl-letter in preference to other combinations when choosing new shortcut keys.

  • Insert, Delete, Home, End, Page Up and Page Down are acceptable shortcut keys for functions that are closely related to those keys' normal system-defined uses. Do not assign them to unrelated functions just because you've run out of other shortcut key combinations, however.

  • Only assign shortcut keys to the most commonly-used actions in your application. Do not try to assign a shortcut key to everything.

  • Choose new shortcut keys to be as mnemonic as possible, as these will be easier to learn and remember. For example, Ctrl-E would be a good shortcut for a menu item called Edit Page.

  • Use Shift-Ctrl-letter for functions that reverse or extend another function. For example, Ctrl-Z and Shift-Ctrl-Z for Undo and Redo.

    [Note]Unicode entry shortcuts

    Note that you cannot use Shift-Ctrl-A-thru-F or Shift-Ctrl-0-thru-9 for your own purposes, as these combinations are used to enter unicode characters in text fields.

  • Do not use Ctrl-number or numbered function keys as shortcut keys, unless the number has some obvious relevance to the action. For example, Ctrl-2 and Ctrl-3 may be acceptable shortcut keys for View->2D View and View->3D View in a 3D modelling application.

  • Do not use Alt-key combinations for shortcut keys, as these may conflict with window manager or menu access keys.

  • Do not use symbols that require Shift or other modifiers as part of a shortcut, for example Ctrl-%. Remember that symbols that can be accessed without a modifier key on your keyboard may be more difficult to access on different international keyboards.

  • Do not assign shortcut keys to menu items that change over time, for example a list of open windows on the Window menu, or a recently-used file list on the File menu. Do assign access keys to these items, however.

  • Do not use any of the standard shortcut keys listed in the section called “Standard Application Shortcut Keys” for your own purposes, even if your application doesn't support those functions. This helps reinforce consistency between all GNOME applications.

Standard Application Shortcut Keys

If your application uses any of the standard functions listed in the following tables, use the recommended standard keyboard shortcut for that function.

Table 10.5. Standard GNOME application shortcut keys and access keys - File menu

FunctionShortcutDescription
NewCtrl-NCreate a new document
OpenCtrl-OOpen a document
SaveCtrl-SSave the current document
PrintCtrl-PPrint the current document
CloseCtrl-WClose the current document
QuitCtrl-QQuit the application

Table 10.6. Standard GNOME application shortcut keys and access keys - Edit menu

FunctionShortcutDescription
UndoCtrl-ZUndo the last operation
RedoShift-Ctrl-ZRedo the last operation
CutCtrl-XCut the selected area and store it in the clipboard
CopyCtrl-CCopy the selected area into the clipboard
PasteCtrl-VPaste contents of clipboard at mouse/cursor position
DuplicateCtrl-UDuplicate the currently-selected items and add them to the same window, without affecting the clipboard
Select AllCtrl-ASelect everything in focused control or window
Invert SelectionCtrl-ISelect everything in focused control or window that was previously unselected, and deselect everything that was previously selected
DeleteDelDelete selection
Find...Ctrl-FFind matches in the current document, highlighting them in-place
Search...Ctrl-F (see note below)Search for matches in multiple documents, files or other external sources
Find NextCtrl-GFind the next match
Replace...Ctrl-HFind and replace matches
RenameF2Switch the selected item's label into edit mode, allowing user to type in a new name.
[Note]Find and Search

If your application requires both Edit->Find and Edit->Search menu items, use Shift-Ctrl-F as the shortcut for Search.

Table 10.7. Standard GNOME application shortcut keys and access keys - View menu

FunctionShortcutDescription
Zoom InCtrl-PlusZoom in on the document Should probably recommend that Ctrl-Equals work too
Zoom OutCtrl-MinusZoom out of the document
Normal SizeCtrl-0Restore to zoom level to normal size (generally 100%)
RefreshCtrl-RRedraw current view of document, without checking if content has changed
ReloadCtrl-R (see note below)Reload the current document, updating content from source if necessary
PropertiesAlt-EnterDisplay the selected object's Properties window. May alternatively appear on the File menu if the document itself is the only object in the application whose properties can be inspected.
[Note]Reload and Refresh

If your application requires both View->Reload and View->Refresh menu items, use Shift-Ctrl-R as the shortcut for Reload.

Table 10.8. Standard GNOME application shortcut keys and access keys - Bookmarks menu

FunctionShortcutDescription
Add BookmarkCtrl-DAdd a bookmark for the current location
Edit Bookmarks...Ctrl-B (see note below)Open a window in which the user can edit and organise saved bookmarks
[Note]Bold and Edit Bookmarks

If your application requires both Format->Bold and Bookmarks->Edit Bookmarks... menu items, use Shift-Ctrl-D as the shortcut for Edit Bookmarks.

Table 10.9. Standard GNOME application shortcut keys and access keys - Go menu

FunctionShortcutDescription
BackAlt-LeftGo to the previous location in the navigation chain
NextAlt-RightGo to the next location in the navigation chain
UpAlt-UpGo up one level in the navigation hierarchy
HomeAlt-HomeGo to the starting page defined by the user or application
Location...Ctrl-LPresent or focus an entry field into which the user can type a new address or location to view

Table 10.10. Standard GNOME application shortcut keys and access keys - Format menu

FunctionShortcutDescription
BoldCtrl-BMake selected text bold/regular
UnderlineCtrl-UUnderline/remove underline from selected text
ItalicCtrl-IMake selected text italic/regular

Table 10.11. Standard GNOME application shortcut keys and access keys - Help menu

FunctionShortcutDescription
ContentsF1Show help contents page for the current application

Standard Window Manager Shortcut Keys

The following shortcut keys are used by many window managers, and should not normally be over-ridden by your application.

Table 10.12. Standard window manager shortcut keys and access keys

FunctionShortcutDescription
Switch primary windowsAlt-Tab, Shift-Alt-TabSwitch focus to the next or previous top level window on the desktop
Switch panelsCtrl-Alt-Tab, Shift-Ctrl-Alt-TabSwitch focus to the next or previous panel on the desktop
Log outCtrl-Alt-DelOpen the session logout confirmation dialog
Window menuAlt-SpaceOpen the window menu
CloseAlt-F4Close the focused window
RestoreAlt-F5Restore the focused to its previous size
Switch secondary windowsAlt-F6, Shift-Alt-F6Switch focus to the next or previous secondary window associated with the application (precise functionality for metacity TBD, see bug 94682)
MoveAlt-F7Move the focused window
ResizeAlt-F8Resize the focused window
MinimizeAlt-F9Minimze the focused window
MaximizeAlt-F10Maximize the focused window
Full ScreenCtrl-F11Show the window in full screen mode, with no border, menubar, toolbar or statusbar

Standard Widget Navigation Shortcut Keys

The following shortcut keys are reserved for keyboard navigation use by the various widgets used in GNOME, and should not normally be over-ridden by your application.

Table 10.13. Standard GNOME keyboard navigation keys for widgets

KeyFunction
Tab, Shift-TabMoves keyboard focus to next/previous control
Ctrl-Tab, Shift-Ctrl-TabMoves keyboard focus out of enclosing widget to next/previous control, in those situations where Tab alone has another function (e.g. GtkTextView)
Ctrl-F1Pop up tooltip for currently-focused control
Shift-F1Show context-sensitive help for currently-focused window or control
F6, Shift-F6Give focus to next/previous pane in a GtkPaned window
F8Give focus to splitter bar in paned window
F10Give focus to window's menu bar
Shift-F10Pop up contextual menu for currently-selected objects
SpaceToggle selected state of focused check box, radio button, or toggle button
ReturnActivate focused button, menu item etc.
Home, EndSelect/move to first item in selected widget
PageUp, Ctrl-PageUp, PageDown, Ctrl-PageDownScroll selected view by one page up/left/down/right

Additional Widget Navigation Shortcut Keys

The following emacs-style navigation shortcut keys are still available in GNOME 2.0 text entry fields (by selecting the "emacs" scheme in the GNOME Keyboard Shortcuts preferences dialog), but are disabled by default. Since some users will still want to use them, do not over-ride them for your own purposes in any situations where a text entry control has focus.

Table 10.14. Emacs-style navigation keys for widgets

KeyFunction
Ctrl-AMove cursor to beginning of line
Ctrl-DDelete character following/under cursor
Ctrl-EMove cursor to end of line
Ctrl-KDelete from cursor to end of line
Ctrl-UDelete current line
Ctrl-WCut to clipboard
Ctrl-YPaste from clipboard
Ctrl-SpaceSet mark
Ctrl-Del, Alt-DDelete from cursor to end of word
Ctrl-BackspaceDelete from cursor to start of word
Alt-SpaceDelete all whitespace around cursor, reinsert single space
Alt-\Delete all whitespace around cursor

Keyboard Interaction with Panel Applications (Applets)

Panels have been fully keyboard navigable since GNOME 2.0. Since your panel application can gain keyboard focus, you must ensure that it is also keyboard navigable.

The rules for panel application keyboard navigation are mostly the same as those for any other window. However, there is one imporant difference:

  • Do not use the the Tab key as the means of moving focus between controls in a panel application. Use the arrow keys for this purpose instead.

When an object on a panel has focus, the Tab key normally moves focus to the next object on the panel. If your panel application also used Tab for its own internal navigation, the user would have to press Ctrl-Tab to move focus out of your panel application instead. This inconsistency would be detremental to the user experience.