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+<!DOCTYPE html><!-- This page is a placeholder for generated extensions api doc. Note:
+ 1) The <head> information in this page is significant, should be uniform
+ across api docs and should be edited only with knowledge of the
+ templating mechanism.
+ 3) All <body>.innerHTML is genereated as an rendering step. If viewed in a
+ browser, it will be re-generated from the template, json schema and
+ authored overview content.
+ 4) The <body>.innerHTML is also generated by an offline step so that this
+ page may easily be indexed by search engines.
+--><html xmlns="http://www.w3.org/1999/xhtml"><head>
+ <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
+ <link href="css/ApiRefStyles.css" rel="stylesheet" type="text/css">
+ <link href="css/print.css" rel="stylesheet" type="text/css" media="print">
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+ </script>
+ <script type="text/javascript" src="js/api_page_generator.js"></script>
+ <script type="text/javascript" src="js/bootstrap.js"></script>
+ <title>Accessibility (a11y) - Google Chrome Extensions - Google Code</title></head>
+ <body> <div id="gc-container" class="labs">
+ <div id="devModeWarning">
+ You are viewing extension docs in chrome via the 'file:' scheme: are you expecting to see local changes when you refresh? You'll need run chrome with --allow-file-access-from-files.
+ </div>
+ <!-- SUBTEMPLATES: DO NOT MOVE FROM THIS LOCATION -->
+ <!-- In particular, sub-templates that recurse, must be used by allowing
+ jstemplate to make a copy of the template in this section which
+ are not operated on by way of the jsskip="true" -->
+ <div style="display:none">
+
+ <!-- VALUE -->
+ <div id="valueTemplate">
+ <dt>
+ <var>paramName</var>
+ <em>
+
+ <!-- TYPE -->
+ <div style="display:inline">
+ (
+ <span class="optional">optional</span>
+ <span class="enum">enumerated</span>
+ <span id="typeTemplate">
+ <span>
+ <a> Type</a>
+ </span>
+ <span>
+ <span>
+ array of <span><span></span></span>
+ </span>
+ <span>paramType</span>
+ <span></span>
+ </span>
+ </span>
+ )
+ </div>
+
+ </em>
+ </dt>
+ <dd class="todo">
+ Undocumented.
+ </dd>
+ <dd>
+ Description of this parameter from the json schema.
+ </dd>
+ <dd>
+ This parameter was added in version
+ <b><span></span></b>.
+ You must omit this parameter in earlier versions,
+ and you may omit it in any version. If you require this
+ parameter, the manifest key
+ <a href="manifest.html#minimum_chrome_version">minimum_chrome_version</a>
+ can ensure that your extension won't be run in an earlier browser version.
+ </dd>
+
+ <!-- OBJECT PROPERTIES -->
+ <dd>
+ <dl>
+ <div>
+ <div>
+ </div>
+ </div>
+ </dl>
+ </dd>
+
+ <!-- FUNCTION PARAMETERS -->
+ <dd>
+ <div></div>
+ </dd>
+
+ </div> <!-- /VALUE -->
+
+ <div id="functionParametersTemplate">
+ <h5>Parameters</h5>
+ <dl>
+ <div>
+ <div>
+ </div>
+ </div>
+ </dl>
+ </div>
+ </div> <!-- /SUBTEMPLATES -->
+
+ <a id="top"></a>
+ <div id="skipto">
+ <a href="#gc-pagecontent">Skip to page content</a>
+ <a href="#gc-toc">Skip to main navigation</a>
+ </div>
+ <!-- API HEADER -->
+ <table id="header" width="100%" cellspacing="0" border="0">
+ <tbody><tr>
+ <td valign="middle"><a href="http://code.google.com/"><img src="images/code_labs_logo.gif" height="43" width="161" alt="Google Code Labs" style="border:0; margin:0;"></a></td>
+ <td valign="middle" width="100%" style="padding-left:0.6em;">
+ <form action="http://www.google.com/cse" id="cse" style="margin-top:0.5em">
+ <div id="gsc-search-box">
+ <input type="hidden" name="cx" value="002967670403910741006:61_cvzfqtno">
+ <input type="hidden" name="ie" value="UTF-8">
+ <input type="text" name="q" value="" size="55">
+ <input class="gsc-search-button" type="submit" name="sa" value="Search">
+ <br>
+ <span class="greytext">e.g. "page action" or "tabs"</span>
+ </div>
+ </form>
+
+ <script type="text/javascript" src="http://www.google.com/jsapi"></script>
+ <script type="text/javascript">google.load("elements", "1", {packages: "transliteration"});</script>
+ <script type="text/javascript" src="http://www.google.com/coop/cse/t13n?form=cse&amp;t13n_langs=en"></script>
+ <script type="text/javascript" src="http://www.google.com/coop/cse/brand?form=cse&amp;lang=en"></script>
+ </td>
+ </tr>
+ </tbody></table>
+
+ <div id="codesiteContent" class="">
+
+ <a id="gc-topnav-anchor"></a>
+ <div id="gc-topnav">
+ <h1>Google Chrome Extensions (<a href="http://code.google.com/labs/">Labs</a>)</h1>
+ <ul id="home" class="gc-topnav-tabs">
+ <li id="home_link">
+ <a href="index.html" title="Google Chrome Extensions home page">Home</a>
+ </li>
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+ <a href="samples.html" title="Sample extensions (with source code)">Samples</a>
+ </li>
+ <li id="group_link">
+ <a href="http://groups.google.com/a/chromium.org/group/chromium-extensions" title="Google Chrome Extensions developer forum">Group</a>
+ </li>
+ </ul>
+ </div> <!-- end gc-topnav -->
+
+ <div class="g-section g-tpl-170">
+ <!-- SIDENAV -->
+ <div class="g-unit g-first" id="gc-toc">
+ <ul>
+ <li><a href="getstarted.html">Getting Started</a></li>
+ <li><a href="overview.html">Overview</a></li>
+ <li><a href="whats_new.html">What's New?</a></li>
+ <li><h2><a href="devguide.html">Developer's Guide</a></h2>
+ <ul>
+ <li>Browser UI
+ <ul>
+ <li><a href="browserAction.html">Browser Actions</a></li>
+ <li><a href="contextMenus.html">Context Menus</a></li>
+ <li><a href="notifications.html">Desktop Notifications</a></li>
+ <li><a href="options.html">Options Pages</a></li>
+ <li><a href="override.html">Override Pages</a></li>
+ <li><a href="pageAction.html">Page Actions</a></li>
+ <li><a href="themes.html">Themes</a></li>
+ </ul>
+ </li>
+ <li>Browser Interaction
+ <ul>
+ <li><a href="bookmarks.html">Bookmarks</a></li>
+ <li><a href="cookies.html">Cookies</a></li>
+ <li><a href="events.html">Events</a></li>
+ <li><a href="history.html">History</a></li>
+ <li><a href="tabs.html">Tabs</a></li>
+ <li><a href="windows.html">Windows</a></li>
+ </ul>
+ </li>
+ <li>Implementation
+ <ul>
+ <li class="leftNavSelected">Accessibility</li>
+ <li><a href="background_pages.html">Background Pages</a></li>
+ <li><a href="content_scripts.html">Content Scripts</a></li>
+ <li><a href="xhr.html">Cross-Origin XHR</a></li>
+ <li><a href="idle.html">Idle</a></li>
+ <li><a href="i18n.html">Internationalization</a></li>
+ <li><a href="messaging.html">Message Passing</a></li>
+ <li><a href="npapi.html">NPAPI Plugins</a></li>
+ </ul>
+ </li>
+ <li>Finishing
+ <ul>
+ <li><a href="hosting.html">Hosting</a></li>
+ <li><a href="external_extensions.html">Other Deployment Options</a></li>
+ </ul>
+ </li>
+ </ul>
+ </li>
+ <li><h2><a href="tutorials.html">Tutorials</a></h2>
+ <ul>
+ <li><a href="tut_debugging.html">Debugging</a></li>
+ <li><a href="tut_analytics.html">Google Analytics</a></li>
+ <li><a href="tut_oauth.html">OAuth</a></li>
+ </ul>
+ </li>
+ <li><h2>Reference</h2>
+ <ul>
+ <li>Formats
+ <ul>
+ <li><a href="manifest.html">Manifest Files</a></li>
+ <li><a href="match_patterns.html">Match Patterns</a></li>
+ <!-- <li>Packages (.crx)</li> -->
+ </ul>
+ </li>
+ <li><a href="api_index.html">chrome.* APIs</a></li>
+ <li><a href="api_other.html">Other APIs</a></li>
+ </ul>
+ </li>
+ <li><h2><a href="samples.html">Samples</a></h2></li>
+ </ul>
+ </div>
+
+ <div class="g-unit" id="gc-pagecontent">
+ <div id="pageTitle">
+ <h1 class="page_title">Accessibility (a11y)</h1>
+ </div>
+ <!-- TABLE OF CONTENTS -->
+ <div id="toc">
+ <h2>Contents</h2>
+ <ol>
+ <li>
+ <a href="#controls">Use accessible UI controls</a>
+ <ol>
+ <li>
+ <a href="#htmlcontrols">Standard controls</a>
+ </li><li>
+ <a href="#aria">ARIA in custom controls</a>
+ </li><li>
+ <a href="#focus">Focus in custom controls</a>
+ </li>
+ </ol>
+ </li><li>
+ <a href="#keyboard"> Support keyboard access </a>
+ <ol>
+ <li>
+ <a href="#navigation"> Navigation </a>
+ </li><li>
+ <a href="#shortcuts"> Shortcuts </a>
+ </li>
+ </ol>
+ </li><li>
+ <a href="#more"> Provide accessible content </a>
+ <ol>
+ <li>
+ <a href="#text">Text</a>
+ </li><li>
+ <a href="#colors">Colors</a>
+ </li><li>
+ <a href="#sound">Sound</a>
+ </li><li>
+ <a href="#images">Images</a>
+ </li>
+ </ol>
+ </li><li>
+ <a href="#examples">Examples</a>
+ <ol>
+ <li style="display: none; ">
+ <a>h3Name</a>
+ </li>
+ </ol>
+ </li>
+ <li style="display: none; ">
+ <a href="#apiReference">API reference</a>
+ <ol>
+ <li>
+ <a href="#properties">Properties</a>
+ <ol>
+ <li>
+ <a href="#property-anchor">propertyName</a>
+ </li>
+ </ol>
+ </li>
+ <li>
+ <a href="#methods">Methods</a>
+ <ol>
+ <li>
+ <a href="#method-anchor">methodName</a>
+ </li>
+ </ol>
+ </li>
+ <li>
+ <a href="#events">Events</a>
+ <ol>
+ <li>
+ <a href="#event-anchor">eventName</a>
+ </li>
+ </ol>
+ </li>
+ <li>
+ <a href="#types">Types</a>
+ <ol>
+ <li>
+ <a href="#id-anchor">id</a>
+ </li>
+ </ol>
+ </li>
+ </ol>
+ </li>
+ </ol>
+ </div>
+ <!-- /TABLE OF CONTENTS -->
+
+ <!-- Standard content lead-in for experimental API pages -->
+ <p id="classSummary" style="display: none; ">
+ For information on how to use experimental APIs, see the <a href="experimental.html">chrome.experimental.* APIs</a> page.
+ </p>
+
+ <!-- STATIC CONTENT PLACEHOLDER -->
+ <div id="static"><div id="pageData-name" class="pageData">Accessibility (a11y)</div>
+<div id="pageData-showTOC" class="pageData">true</div>
+
+<p>
+When you design an extension,
+try to make it as accessible as possible
+to people with disabilities such as
+visual impairment, hearing loss, and limited dexterity.
+</p>
+
+<p>
+Everyone — not just people with special needs —
+can benefit from the alternative access modes
+that accessible extensions provide.
+For example, keyboard shortcuts are important
+for blind people and people with limited dexterity,
+but they also help power users get things done
+more quickly without using a mouse.
+Captions and transcripts give deaf people access to audio content,
+but they are also useful to language learners.
+</p>
+
+<p>
+People can interact with your extension in a variety of ways.
+They might use a standard monitor, keyboard, and mouse,
+or they might use a screen magnifier and just a keyboard.
+Another possibility is a <em>screen reader</em>,
+an assistive application tool that interprets
+what's displayed onscreen
+for a blind or visually impaired user.
+A screen reader might speak out loud or produce Braille output.
+</p>
+
+<p>
+Although you can't predict what tools people will use,
+by following a few simple guidelines
+you can write an extension that is
+more likely to be accessible to more people.
+The guidelines on this page aren't going to
+make your extension accessible for absolutely everyone,
+but they're a good starting point.
+</p>
+
+
+<h2 id="controls">Use accessible UI controls</h2>
+
+<p>
+First, use UI controls that support accessibility.
+The easiest way to get an accessible control is to use a
+standard HTML control.
+If you need to build a custom control,
+keep in mind that it's much easier
+to make the control accessible from the beginning
+than to go back and add accessibility support later.
+</p>
+
+<h3 id="htmlcontrols">Standard controls</h3>
+
+<p>
+Try to use standard HTML UI controls whenever possible.
+Standard HTML controls (shown in the following figure)
+are keyboard accessible, scale easily,
+and are generally understood by screen readers.
+</p>
+
+<img src="images/a11y/standard-html-controls.png" width="550" height="350" alt="Screenshots and code for button, checkbox, radio, text, select/option, and link">
+
+
+<h3 id="aria">ARIA in custom controls</h3>
+
+<p>
+ARIA is a specification for making UI controls accessible to screen readers
+by means of a standard set of DOM attributes.
+These attributes provide clues to the screen reader
+about the function and current state of controls on a web page.
+ARIA is a
+<a href=" http://www.w3.org/WAI/intro/aria">work in progress at the W3C</a>.
+</p>
+
+<p>
+Adding ARIA support to custom controls in your extension
+involves modifying DOM elements to add attributes
+Google Chrome uses
+to raise events during user interaction.
+Screen readers respond to these events
+and describe the function of the control.
+The DOM attributes specified by ARIA are classified into
+<em>roles</em>, <em>states</em>, and <em>properties</em>.
+</p>
+
+<p>
+The ARIA attribute <em>role</em>
+is an indication of the control type
+and describes the way the control should behave.
+It is expressed with the DOM attribute <code>role</code>,
+with a value set to one of the pre-defined ARIA role strings.
+Because ARIA roles are static,
+the role attribute should not change its value.
+</p>
+
+<p>
+The <a href="http://www.w3.org/WAI/PF/aria/roles">ARIA Role Specification</a>
+holds detailed information on how to pick the correct role.
+For example, if your extension includes a toolbar,
+set the <code>role</code> attribute of the toolbar's DOM element as follows:
+</p>
+
+<pre>&lt;div role="toolbar"&gt;
+</pre>
+
+<p>
+ARIA attributes are also used to describe
+the current state and properties of controls of a particular role.
+A <em>state</em> is dynamic and should be updated during user interaction.
+For example, a control with the role "checkbox"
+could be in the states "checked" or "unchecked".
+A <em>property</em> is not generally dynamic,
+but is similar to a state
+in that it expresses specific information about a control.
+For more information on ARIA states and properties,
+refer to the
+<a href="http://www.w3.org/TR/wai-aria/states_and_properties">W3C States and Properties specification</a>.
+</p>
+
+
+<p class="note">
+<b>Note:</b>
+You don't have to use
+all of the states and properties available for a particular role.
+</p>
+
+<p>
+Here's an example of adding
+the ARIA property <code>aria-activedescendant</code>
+to the example toolbar control:
+</p>
+
+<pre>&lt;div role="toolbar" tabindex="0" aria-activedescendant="button1"&gt;
+</pre>
+
+<p>
+The
+<a href="http://www.w3.org/WAI/PF/aria/states_and_properties#aria-activedescendant"><code>aria-activedescendant</code></a>
+property specifies which child of the toolbar receives focus
+when the toolbar receives focus.
+In this example, the toolbar's first button
+(which has the <code>id</code> "button1")
+is the child that gets focus.
+The code <code>tabindex="0"</code>
+specifies that the toolbar
+receives focus in document order.
+</p>
+
+<p>
+Here's the complete specification for the example toolbar:
+</p>
+
+<pre>&lt;div role="toolbar" tabindex="0" aria-activedescendant="button1"&gt;
+ &lt;img src="buttoncut.png" role="button" alt="cut" id="button1"&gt;
+ &lt;img src="buttoncopy.png" role="button" alt="copy" id="button2"&gt;
+ &lt;img src="buttonpaste.png" role="button" alt="paste" id="button3"&gt;
+&lt;/div&gt;
+</pre>
+
+<p>
+Once ARIA roles, states, and properties are added to the DOM of a control,
+Google Chrome raises the appropriate events to the screen reader.
+Because ARIA support is still a work in progress,
+Google Chrome might not raise an event for every ARIA property,
+and screen readers might not recognize all of the events being raised.
+You can find more information on ARIA support in Google Chrome in the
+<a href="http://www.chromium.org/developers/design-documents/accessibility#TOC-WAI-ARIA-Support">Chromium Accessibility Design Document</a>.
+</p>
+
+<p>
+For a quick tutorial on adding ARIA controls to custom controls, see
+<a href="http://www.w3.org/2010/Talks/www2010-dsr-diy-aria/">Dave Raggett's presentation from WWW2010</a>.
+
+</p><h3 id="focus">Focus in custom controls</h3>
+
+<p>
+Make sure that operation and navigation controls of your extension
+can receive keyboard focus.
+Operation controls might include
+buttons, trees, and list boxes.
+Navigation controls might include tabs and menu bars.
+</p>
+
+<p>
+By default, the only elements in the HTML DOM
+that can receive keyboard focus
+are anchors, buttons, and form controls.
+However, setting the HTML attribute <code>tabIndex</code> to <code>0</code>
+places DOM elements in the default tab sequence,
+enabling them to receive keyboard focus.
+For example:
+</p>
+
+<pre><em>element</em>.tabIndex = 0
+</pre>
+
+<p>
+Setting <code>tabIndex = -1</code> removes the element from the tab sequence
+but still allows the element to receive keyboard focus programmatically.
+Here's an example of setting keyboard focus:
+</p>
+
+<pre><em>element</em>.focus();
+</pre>
+
+<p>
+Ensuring that your custom UI controls include keyboard support
+is important not only for users who don't use the mouse
+but also because screen readers use keyboard focus
+to determine which control to describe.
+</p>
+
+<h2 id="keyboard"> Support keyboard access </h2>
+
+<p>
+People should be able to use your extension
+even if they can't or don't want to use a mouse.
+</p>
+
+<h3 id="navigation"> Navigation </h3>
+
+<p>
+Check that the user can navigate between
+the different parts of your extension
+without using the mouse.
+Also check that any popups on page actions or browser actions
+are keyboard navigable.
+</p>
+
+<p class="note">
+<b>Note:</b>
+We're improving keyboard accessibility to Google Chrome's interface;
+keyboard navigation to the icons of page actions and browser actions
+is expected in Google Chrome 6.
+For details, see
+<a href="#builtin">Built-in toolbar navigation</a>.
+</p>
+
+<p>
+Make sure that it's easy to see
+which part of the interface has keyboard focus.
+Usually a focus outline moves around the interface,
+but if you’re using CSS heavily this outline might be suppressed
+or the contrast might be reduced.
+Two examples of focus outline follow.
+</p>
+
+<img src="images/a11y/focus-outline-2.png" width="200" height="75" alt="A focus outline on a Search button">
+<br>
+<img src="images/a11y/focus-outline.png" width="400" height="40" alt="A focus outline on one of a series of links">
+
+<h4 id="builtin"> Built-in toolbar navigation </h4>
+
+<p>
+Here are the keyboard shortcuts that we expect to be in Google Chrome 6.
+You can try them out now in the Dev channel.
+</p>
+
+<p>
+</p><table>
+ <tbody><tr>
+ <td> <b>Alt+Shift+T</b> </td>
+ <td> Focus on the first tool in the main toolbar. </td></tr>
+
+ <tr><td> <b>Tab</b>, <b>Shift+Tab</b>, <b>Home</b>, <b>End</b> </td>
+ <td> Move around in the toolbar,
+ including focusing on page actions and browser actions. </td></tr>
+
+ <tr><td> <b>Left&nbsp;arrow</b>, <b>Right&nbsp;arrow</b> </td>
+ <td> Move around in the toolbar,
+ unless you're in an edit box like the location bar,
+ where those keys are used for text editing. </td></tr>
+
+ <tr><td> <b>Space</b>, <b>Enter</b> </td>
+ <td> Activate toolbar buttons,
+ including page actions and browser actions. </td></tr>
+
+ <tr><td> <b>Context&nbsp;menu&nbsp;key</b>, <b>Shift+F10</b> </td>
+ <td> Open a toolbar button's context menu. </td></tr>
+
+ <tr><td> <b>Escape</b> </td>
+ <td> Return focus from the toolbar to the previous location. </td></tr>
+
+ <tr><td> <b>F6</b>, <b>Shift+F6</b> </td>
+ <td> Switch focus to the next keyboard-accessible pane,
+ where panes include the
+ main web content,
+ toolbar,
+ and bookmarks bar (if visible). </td></tr>
+
+</tbody></table>
+<p></p>
+
+
+<h3 id="shortcuts"> Shortcuts </h3>
+
+<p>
+Although the most common keyboard navigation strategy involves
+using the Tab key to move focus through the extension interface,
+that's not always the easiest or most efficient way
+to use the interface.
+You can make keyboard navigation easier
+by providing explicit keyboard shortcuts.
+</p>
+
+<p>
+To implement shortcuts,
+connect keyboard event listeners to your controls.
+A good reference is the DHTML Style Guide Working Group’s
+<a href="http://dev.aol.com/dhtml_style_guide">guidelines for keyboard shortcuts</a>.
+</p>
+
+<p>
+A good way to ensure discoverability of keyboard shortcuts
+is to list them somewhere.
+Your extension’s
+<a href="options.html">Options page</a>
+might be a good place to do this.
+</p>
+
+<p>
+For the example toolbar,
+a simple JavaScript keyboard handler could look like the following.
+Note how the ARIA property <code>aria-activedescendant</code>
+is updated in response to user input
+to reflect the current active toolbar button.
+</p>
+
+<pre>&lt;head&gt;
+&lt;script&gt;
+ function optionKeyEvent(event) {
+ var tb = event.target;
+ var buttonid;
+
+ ENTER_KEYCODE = 13;
+ RIGHT_KEYCODE = 39;
+ LEFT_KEYCODE = 37;
+ // Partial sample code for processing arrow keys.
+ if (event.type == "keydown") {
+ // Implement circular keyboard navigation within the toolbar buttons
+ if (event.keyCode == ENTER_KEYCODE) {
+ ExecuteButtonAction(getCurrentButtonID());
+ <em>// getCurrentButtonID defined elsewhere </em>
+ } else if (event.keyCode == event.RIGHT_KEYCODE) {
+ // Change the active toolbar button to the one to the right (circular).
+ var buttonid = getNextButtonID();
+ <em>// getNextButtonID defined elsewhere </em>
+ tb.setAttribute("aria-activedescendant", buttonid);
+ } else if (event.keyCode == event.LEFT_KEYCODE) {
+ // Change the active toolbar button to the one to the left (circular).
+ var buttonid = getPrevButtonID();
+ <em>// getPrevButtonID defined elsewhere </em>
+ tb.setAttribute("aria-activedescendant", buttonid);
+ } else {
+ return true;
+ }
+ return false;
+ }
+}
+&lt;/script&gt;
+
+&lt;div role="toolbar" tabindex="0" aria-activedescendant="button1" id="tb1"
+ onkeydown="return optionKeyEvent(event);"
+ onkeypress="return optionKeyEvent(event);"&gt;
+ &lt;img src="buttoncut" role="button" alt="cut" id="button1"&gt;
+ &lt;img src="buttoncopy" role="button" alt="copy" id="button1"&gt;
+ &lt;img src="buttonpaste" role="button" alt="paste" id="button1"&gt;
+&lt;/div&gt;
+</pre>
+
+
+<h2 id="more"> Provide accessible content </h2>
+
+
+<p>
+The remaining guidelines might be familiar
+because they reflect good practices for all web content,
+not just extensions.
+</p>
+
+<h3 id="text">Text</h3>
+
+<p>
+Evaluate your use of text in your extension.
+Many people might find it helpful
+if you provide a way to increase the text size within your extension.
+If you are using keyboard shortcuts,
+make sure that they don't interfere with
+the zoom shortcuts built into Google Chrome.
+</p>
+
+<p>
+As an indicator of the flexibility of your UI,
+apply the <a href="http://www.w3.org/TR/2008/REC-WCAG20-20081211/#visual-audio-contrast-scale">200% test</a>.
+If you increase the text size or page zoom 200%,
+is your extension still usable?
+</p>
+
+<p>
+Also, avoid baking text into images:
+users cannot modify the size of text displayed as an image,
+and screenreaders cannot interpret images.
+Consider using a web font instead,
+such as one of the fonts collected in the
+<a href="http://code.google.com/apis/webfonts/">Google Font API</a>.
+Text styled in a web font is searchable,
+scales to different sizes,
+and is accessible to people using screen readers.
+</p>
+
+<h3 id="colors">Colors</h3>
+
+<p>
+Check that there is sufficient contrast between
+background color and foreground/text color in your extension.
+<a href="http://snook.ca/technical/colour_contrast/colour.html">This contrast checking tool</a>
+checks whether your background and foreground colors
+provide appropriate contrast.
+If you’re developing in a Windows environment,
+you can also enable High Contrast Mode
+to check the contrast of your extension.
+When evaluating contrast,
+verify that every part of your extension that relies on
+color or graphics to convey information is clearly visible.
+For specific images, you can use a tool such as the
+<a href="http://www.vischeck.com/vischeck/">Vischeck simulation tool</a>
+to see what an image looks like in various forms of color deficiency.
+</p>
+
+<p>
+You might consider offering different color themes,
+or giving the user the ability to customize the color scheme
+for better contrast.
+</p>
+
+<h3 id="sound">Sound</h3>
+
+<p>
+If your extension relies upon sound or video to convey information,
+ensure that captions or a transcript are available.
+See the
+<a href="http://www.dcmp.org/ciy/">Described and Captioned Media Program guidelines</a>
+for more information on captions.
+</p>
+
+<h3 id="images">Images</h3>
+
+<p>
+Provide informative alt text for your images.
+For example:
+</p>
+
+<pre>&lt;img src="img.jpg" alt="The logo for the extension"&gt;
+</pre>
+
+<p>
+Use the alt text to state the purpose of the image
+rather than as a literal description of the contents of an image.
+Spacer images or purely decorative images
+should have blank ("") alt text
+or be removed from the HTML entirely and placed in the CSS.
+</p>
+
+<p>
+If you must use text in an image,
+include the image text in the alt text.
+A good resource to refer to is the
+<a href="http://www.webaim.org/techniques/alttext/">WebAIM article on appropriate alt text</a>.
+
+</p><h2 id="examples">Examples</h2>
+
+<p>
+For an example that implements keyboard navigation and ARIA properties, see
+<a href="http://src.chromium.org/viewvc/chrome/trunk/src/chrome/common/extensions/docs/examples/extensions/news_a11y/">examples/extensions/news_a11y</a>
+(compare it to
+<a href="http://src.chromium.org/viewvc/chrome/trunk/src/chrome/common/extensions/docs/examples/extensions/news/">examples/extensions/news</a>).
+For more examples and for help in viewing the source code,
+see <a href="samples.html">Samples</a>.
+
+</p></div>
+
+ <!-- API PAGE -->
+ <div class="apiPage" style="display: none; ">
+ <a name="apiReference"></a>
+ <h2>API reference: chrome.apiname </h2>
+
+ <!-- PROPERTIES -->
+ <div class="apiGroup">
+ <a name="properties"></a>
+ <h3 id="properties">Properties</h3>
+
+ <div>
+ <a></a>
+ <h4>getLastError</h4>
+ <div class="summary">
+ <!-- Note: intentionally longer 80 columns -->
+ <span>chrome.extension</span><span>lastError</span>
+ </div>
+ <div>
+ </div>
+ </div>
+
+ </div> <!-- /apiGroup -->
+
+ <!-- METHODS -->
+ <div class="apiGroup" id="methods">
+ <a name="methods"></a>
+ <h3>Methods</h3>
+
+ <!-- iterates over all functions -->
+ <div class="apiItem">
+ <a></a> <!-- method-anchor -->
+ <h4>method name</h4>
+
+ <div class="summary"><span>void</span>
+ <!-- Note: intentionally longer 80 columns -->
+ <span>chrome.module.methodName</span>(<span><span>, </span><span></span>
+ <var><span></span></var></span>)</div>
+
+ <div class="description">
+ <p class="todo">Undocumented.</p>
+ <p>
+ A description from the json schema def of the function goes here.
+ </p>
+
+ <!-- PARAMETERS -->
+ <h4>Parameters</h4>
+ <dl>
+ <div>
+ <div>
+ </div>
+ </div>
+ </dl>
+
+ <!-- RETURNS -->
+ <h4>Returns</h4>
+ <dl>
+ <div>
+ <div>
+ </div>
+ </div>
+ </dl>
+
+ <!-- CALLBACK -->
+ <div>
+ <div>
+ <h4>Callback function</h4>
+ <p>
+ The callback <em>parameter</em> should specify a function
+ that looks like this:
+ </p>
+ <p>
+ If you specify the <em>callback</em> parameter, it should
+ specify a function that looks like this:
+ </p>
+
+ <!-- Note: intentionally longer 80 columns -->
+ <pre>function(<span>Type param1, Type param2</span>) <span class="subdued">{...}</span>;</pre>
+ <dl>
+ <div>
+ <div>
+ </div>
+ </div>
+ </dl>
+ </div>
+ </div>
+
+ <!-- MIN_VERSION -->
+ <p>
+ This function was added in version <b><span></span></b>.
+ If you require this function, the manifest key
+ <a href="manifest.html#minimum_chrome_version">minimum_chrome_version</a>
+ can ensure that your extension won't be run in an earlier browser version.
+ </p>
+ </div> <!-- /description -->
+
+ </div> <!-- /apiItem -->
+
+ </div> <!-- /apiGroup -->
+
+ <!-- EVENTS -->
+ <div class="apiGroup">
+ <a name="events"></a>
+ <h3 id="events">Events</h3>
+
+ <!-- iterates over all events -->
+ <div class="apiItem">
+ <a></a>
+ <h4>event name</h4>
+
+ <div class="summary">
+ <!-- Note: intentionally longer 80 columns -->
+ <span class="subdued">chrome.bookmarks</span><span>onEvent</span><span class="subdued">.addListener</span>(function(<span>Type param1, Type param2</span>) <span class="subdued">{...}</span>);
+ </div>
+
+ <div class="description">
+ <p class="todo">Undocumented.</p>
+ <p>
+ A description from the json schema def of the event goes here.
+ </p>
+
+ <!-- PARAMETERS -->
+ <h4>Parameters</h4>
+ <dl>
+ <div>
+ <div>
+ </div>
+ </div>
+ </dl>
+
+ </div> <!-- /decription -->
+
+ </div> <!-- /apiItem -->
+
+ </div> <!-- /apiGroup -->
+
+ <!-- TYPES -->
+ <div class="apiGroup">
+ <a name="types"></a>
+ <h3 id="types">Types</h3>
+
+ <!-- iterates over all types -->
+ <div class="apiItem">
+ <a></a>
+ <h4>type name</h4>
+
+ <div>
+ </div>
+
+ </div> <!-- /apiItem -->
+
+ </div> <!-- /apiGroup -->
+
+ </div> <!-- /apiPage -->
+ </div> <!-- /gc-pagecontent -->
+ </div> <!-- /g-section -->
+ </div> <!-- /codesiteContent -->
+ <div id="gc-footer" --="">
+ <div class="text">
+ <p>
+ Except as otherwise <a href="http://code.google.com/policies.html#restrictions">noted</a>,
+ the content of this page is licensed under the <a rel="license" href="http://creativecommons.org/licenses/by/3.0/">Creative Commons
+ Attribution 3.0 License</a>, and code samples are licensed under the
+ <a rel="license" href="http://code.google.com/google_bsd_license.html">BSD License</a>.
+ </p>
+ <p>
+ ©2010 Google
+ </p>
+
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