Restructure TopLeftMenu for accessibility and autofocus it

We use a trick with refs to automatically focus the element, also making use of mx_HiddenFocusable to hide the unnecessary outline. 

The menu itself has been restructured to hide some elements from screen readers (reduce noise) and to have a single unordered list. Screen readers mention when the user "enters" a list, and each item was previously saying "enter list <action>" when it should have just been "<action>".

By focusing automatically, the keyboard can be used to go up/down the menu as may be expected by keyboard users.

src/components/views/context_menus/TopLeftMenu.js

@@ -23,6 +23,7 @@ import Modal from "../../../Modal";
 import SdkConfig from '../../../SdkConfig';
 import { getHostingLink } from '../../../utils/HostingLink';
 import MatrixClientPeg from '../../../MatrixClientPeg';
+import {focusCapturedRef} from "../../../utils/Accessibility";
 
 export class TopLeftMenu extends React.Component {
     static propTypes = {
@@ -61,44 +62,48 @@ export class TopLeftMenu extends React.Component {
                 {_t(
                     "<a>Upgrade</a> to your own domain", {},
                     {
-                        a: sub => <a href={hostingSignupLink} target="_blank" rel="noopener">{sub}</a>,
+                        a: sub => <a href={hostingSignupLink} target="_blank" rel="noopener" tabIndex="0">{sub}</a>,
                     },
                 )}
-                <a href={hostingSignupLink} target="_blank" rel="noopener">
+                <a href={hostingSignupLink} target="_blank" rel="noopener" aria-hidden={true}>
                     <img src={require("../../../../res/img/external-link.svg")} width="11" height="10" alt='' />
                 </a>
             </div>;
         }
 
-        let homePageSection = null;
+        let homePageItem = null;
         if (this.hasHomePage()) {
-            homePageSection = <ul className="mx_TopLeftMenu_section_withIcon">
-                <li className="mx_TopLeftMenu_icon_home" onClick={this.viewHomePage}>{_t("Home")}</li>
-            </ul>;
+            homePageItem = <li className="mx_TopLeftMenu_icon_home" onClick={this.viewHomePage} tabIndex={0}>
+                {_t("Home")}
+            </li>;
         }
 
-        let signInOutSection;
+        let signInOutItem;
         if (isGuest) {
-            signInOutSection = <ul className="mx_TopLeftMenu_section_withIcon">
-                <li className="mx_TopLeftMenu_icon_signin" onClick={this.signIn}>{_t("Sign in")}</li>
-            </ul>;
+            signInOutItem = <li className="mx_TopLeftMenu_icon_signin" onClick={this.signIn} tabIndex={0}>
+                {_t("Sign in")}
+            </li>;
         } else {
-            signInOutSection = <ul className="mx_TopLeftMenu_section_withIcon">
-                <li className="mx_TopLeftMenu_icon_signout" onClick={this.signOut}>{_t("Sign out")}</li>
-            </ul>;
+            signInOutItem = <li className="mx_TopLeftMenu_icon_signout" onClick={this.signOut} tabIndex={0}>
+                {_t("Sign out")}
+            </li>;
         }
 
-        return <div className="mx_TopLeftMenu">
-            <div className="mx_TopLeftMenu_section_noIcon">
+        const settingsItem = <li className="mx_TopLeftMenu_icon_settings" onClick={this.openSettings} tabIndex={0}>
+            {_t("Settings")}
+        </li>;
+
+        return <div className="mx_TopLeftMenu mx_HiddenFocusable" tabIndex={0} ref={focusCapturedRef}>
+            <div className="mx_TopLeftMenu_section_noIcon" aria-readonly={true}>
                 <div>{this.props.displayName}</div>
-                <div className="mx_TopLeftMenu_greyedText">{this.props.userId}</div>
+                <div className="mx_TopLeftMenu_greyedText" aria-hidden={true}>{this.props.userId}</div>
                 {hostingSignup}
             </div>
-            {homePageSection}
             <ul className="mx_TopLeftMenu_section_withIcon">
-                <li className="mx_TopLeftMenu_icon_settings" onClick={this.openSettings}>{_t("Settings")}</li>
+                {homePageItem}
+                {settingsItem}
+                {signInOutItem}
             </ul>
-            {signInOutSection}
         </div>;
     }
 

src/utils/Accessibility.js

@@ -0,0 +1,19 @@
+/*
+Copyright 2019 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+export function focusCapturedRef(ref) {
+    if (ref) ref.focus();
+}