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Accessibility features of Firefox

From MozillaZine Knowledge Base

Firefox includes many features to make the browser and web content accessible to all users, including those who have low vision, no vision, or limited ability to use a keyboard or mouse.

In addition to the information and resources listed in this article, you may also post accessibility questions to the Firefox Support forum.

Contents

Using the keyboard

Keyboard shortcuts

A list of common keyboard shortcuts is can be accessed from the Firefox Help menu ("Help -> Help Contents" or F1) and online. A comparison chart of keyboard shortcuts implemented in Firefox, Internet Explorer, Opera, and other popular browsers can be found here.

Note that, in the examples below, 'accel' means the 'Ctrl' key on Windows, and 'Cmd' on Mac. On Unix, 'accel' usually means Ctrl, but it can be set to Alt [1].

Allow text to be selected with the keyboard

Allow text to be selected with the keyboard allows you to move through web content as if you were inside a read-only editor. You can use the keyboard to select web content and copy it to the clipboard. You can enable this feature by selecting Tools/Options (or Preferences on Mac), opening the "General" tab in the "Advanced" panel, and checking the "Allow text to be selected with the keyboard" option.

You can press F7 at any time to turn this feature on or off. When you press F7, Firefox will ask if you really want to turn on this feature. You can disable this prompt by selecting "Don't show this dialog again."

You can fine-tune the behavior of Allow text to be selected with the keyboard with these preferences:

Begin finding when you begin typing

Begin finding when you begin typing allows you to quickly navigate to text or hyperlinks in a web page without opening a separate dialog. This feature has two modes. Press / and start typing to search all text on the current page, or press ' before your string to search hyperlinks only. Firefox will highlight matching text or hyperlinks as you type.

The following keyboard shortcuts control this feature:

  • Type more characters to narrow your search. Firefox will highlight the next matching hyperlink or text or alert you that nothing matched.
  • Press accel + G or F3 to find the next occurrence of your current search string.
  • Press accel + shift + G or shift + F3 to find the previous occurrence of your current search string.
  • Press Backspace to undo the last character you typed. Firefox will back up to the previously highlighted text.
  • Press Esc to cancel a search. You can also cancel a search by changing focus, scrolling the page with the mouse or keyboard, or simply waiting for the timeout.

You can change the default behavior of this feature by selecting Tools/Options (or Preferences on Mac), opening the "General" tab of the "Advanced" panel, and checking the "Begin finding when you begin typing" option. If this option is checked, you can start typing at any time to auto-start an inline search. By default auto-started searches look for all text on the page. You can still explicitly press ' or / to start finding in one mode or the other.

You can use this feature to get to buttons, text boxes and other form controls. Search for the text immediately before the form control you want and press Tab. Pressing Tab automatically exits the search and sets focus to the next form field or button after the highlighted text.

You can fine-tune the behavior of Begin finding when you begin typing with these preferences:

Fonts and colors

Overriding page fonts

Some web sites may display text in fonts that are difficult to read, and other sites may rely on the browser's default fonts. You can set your default fonts by going to Tools/Options (or Preferences on Mac), selecting the "Content" panel, and selecting a default font and size in the "Fonts & Colors" section.

Immediately after the default font and size selection, you can click the "Advanced..." button to specify default fonts for different styles, including serif, sans-serif, and monospace. However, many web pages specify their own fonts, so your choices here will have no effect on such pages. To override the fonts defined by such pages, uncheck the "Allow pages to choose their own fonts, instead of my selections above" option.

A button for "Page Fonts" can be created with Custom Toolbar Buttons Maker , button has a large "A" (toggles on/off).

Note that some web pages may display incorrectly depending on your choice of a default font.

Setting a minimum font size

Some web sites may display text which is too small to read comfortably. To make such pages easier to read, you can set a minimum font size. On web pages that try to display text smaller than this size, Firefox will enlarge the text to your chosen size.

To set a minimum font size, go to Tools/Options (or Preferences on Mac) and select the "Content" panel. In the "Fonts & Colors" section, immediately after the default font and size selection, click the "Advanced" button. You can specify a minimum font size from the dropdown menu.

Note that some web pages may display incorrectly depending on your choice of a minimum font size.

Resizing page text

You can temporarily change the size of text on any web page in the View > Text Size menu. The new size will remain in effect until you close your browser window or tab, even if you navigate to a different web site.

The following keyboard shortcuts control text size. As noted above, 'accel' means the 'Ctrl' key on Windows and, usually, on Unix, and the 'Cmd' key on Mac.

  • Press accel + + to increase the text size. This zooms the text to 120% of its original size, then 150%, 200%, 300%, 450%, 675%, 1013%, and 1519%.
  • Press accel + - to decrease the text size. This zooms the text to 90% of its original size, then 50%, 33%, 22%, 15%, 10%, 7%, 4%, 3%, 2%, and 1%.
  • Press accel + 0 to reset the text size to the web page's default size.

Note that some web pages may display incorrectly if you increase or decrease the text size. In Firefox 3: When Text and Images are zoomed together by default, some column widths or other containers may be dependent upon image size, so enlarging both may cause page to enlarge horizontally forcing use of horizontal scrolling to see text that would normally wrap within a smaller area.

Additional information can be found in Zoom text of web pages.

Overriding page colors

Some web sites may display text and background colors that are difficult to read, and other sites may rely on the browser's default colors. You can set your default colors by going to Tools/Options (or Preferences on Mac) and selecting the "Content" panel. In the "Fonts & Colors" section, click the "Colors..." button. Here you can set default text and background colors, as well as default colors for visited and unvisited hyperlinks. You can also specify whether hyperlinks should be underlined.

However, many web pages set their own colors, so your choices will have no effect. To override the colors defined by web pages, uncheck the "Allow pages to choose their own colors, instead of my selections above" option.

A button for "Page Colours" can be created with Custom Toolbar Buttons Maker , button has a tri-color color wheel (toggles on/off).

Additional information can be found in Use my colors for some conceptual alternatives to use of Tools, Options, Content, Fonts and Colors to specify font, links, and background colors and whether to allow pages to override your default color choices.

Overriding all page formatting

To override all page styling (chrome) to use your default colors, fonts, and Firefox's default style page go to "View" menu > Page Style > No Style.

A toggle button can be created by the "Read Easily extension with a large red "A", or a "Toggle Styles" button can be created with Custom Toolbar Buttons Maker.

Readability features can be toggled with either a bookmarklet or an extension to make reading on the Web more enjoyable by removing the clutter around what you are reading, enlarging text, and eliminating most images and videos to show only the essential text of a web page.


Using a high contrast theme

On Windows and Linux-based systems, Firefox automatically detects if you are using a high contrast theme and displays everything in your high contrast color scheme. This overrides all other other browser or web page settings, and it affects the Firefox interface itself (all menus, windows, and dialog boxes) and the content of any web page you visit.

To use a High Contrast theme on Windows, go to Start Menu > Control Panel > Accessibility Options > Display and check the "Use High Contrast" option.

Controlling web content

Turning Off Java applets

Some web pages provide a rich interactive experience with Java applets. However, some users that rely on keyboard navigation may experience problems with some Java applets that automatically set focus and do not provide a way to "break out" of the applet and navigate to the rest of the web page. If this is a problem for you, you can disable Java by going to Tools/Options (or Preferences on Mac), selecting the "Content" and unchecking the "Enable Java" option.

Restricting JavaScript behavior

You can turn off JavaScript entirely by going to Tools/Options (or Preferences on Mac), selecting the "Content" panel, and unchecking "Enable JavaScript". Some web pages rely on JavaScript and may not work properly if JavaScript is disabled.

If you do not wish to disable JavaScript entirely, there are also a number of advanced JavaScript settings to restrict the behavior of scripts. Immediately after the "Enable JavaScript" checkbox, click the "Advanced" button to open the "Advanced JavaScript Settings" window. Here you can control whether scripts are allowed to move or resize existing windows, raise or lower windows, disable or replace context menus, hide the status bar, or change status bar text.

Advanced accessibility preferences

Controlling focused elements

Controlling access keys

Fine-tuning mouse behavior

Customizing scrollbars

Fine-tuning web content

Scrolling behavior

Spell check behavior

See also

External links