improve list accessibility

fixes #17113

src/vs/base/browser/ui/list/listPaging.ts

@@ -7,7 +7,7 @@ import 'vs/css!./list';
 import { IDisposable } from 'vs/base/common/lifecycle';
 import { range } from 'vs/base/common/arrays';
 import { IDelegate, IRenderer, IFocusChangeEvent, ISelectionChangeEvent } from './list';
-import { List } from './listWidget';
+import { List, IListOptions } from './listWidget';
 import { IPagedModel } from 'vs/base/common/paging';
 import Event, { mapEvent } from 'vs/base/common/event';
 
@@ -67,10 +67,11 @@ export class PagedList<T> {
 	constructor(
 		container: HTMLElement,
 		delegate: IDelegate<number>,
-		renderers: IPagedRenderer<T, any>[]
+		renderers: IPagedRenderer<T, any>[],
+		options: IListOptions = {}
 	) {
 		const pagedRenderers = renderers.map(r => new PagedRenderer<T, ITemplateData<T>>(r, () => this.model));
-		this.list = new List(container, delegate, pagedRenderers);
+		this.list = new List(container, delegate, pagedRenderers, options);
 	}
 
 	get onFocusChange(): Event<IFocusChangeEvent<T>> {

src/vs/base/browser/ui/list/listWidget.ts

@@ -116,7 +116,7 @@ class FocusTrait<T> extends Trait<T> {
 
 	renderElement(element: T, index: number, container: HTMLElement): void {
 		super.renderElement(element, index, container);
-		container.setAttribute('role', 'option');
+		container.setAttribute('role', 'treeitem');
 		container.setAttribute('id', this.getElementId(index));
 	}
 }
@@ -201,6 +201,7 @@ class Controller<T> implements IDisposable {
 }
 
 export interface IListOptions extends IListViewOptions {
+	ariaLabel?: string;
 }
 
 const DefaultOptions: IListOptions = {};
@@ -245,13 +246,17 @@ export class List<T> implements IDisposable {
 		});
 
 		this.view = new ListView(container, delegate, renderers, options);
-		this.view.domNode.setAttribute('role', 'listbox');
+		this.view.domNode.setAttribute('role', 'tree');
 		this.view.domNode.tabIndex = 0;
 		this.controller = new Controller(this, this.view);
 		this.disposables = [this.focus, this.selection, this.view, this.controller];
 
 		this._onDOMFocus = domEvent(this.view.domNode, 'focus');
 		this.onFocusChange(this._onFocusChange, this, this.disposables);
+
+		if (options.ariaLabel) {
+			this.view.domNode.setAttribute('aria-label', options.ariaLabel);
+		}
 	}
 
 	splice(start: number, deleteCount: number, ...elements: T[]): void {
@@ -418,7 +423,16 @@ export class List<T> implements IDisposable {
 	}
 
 	private _onFocusChange(): void {
-		DOM.toggleClass(this.view.domNode, 'element-focused', this.focus.get().length > 0);
+		const focus = this.focus.get();
+
+		if (focus.length > 0) {
+			this.view.domNode.setAttribute('aria-activedescendant', this.getElementId(focus[0]));
+		} else {
+			this.view.domNode.removeAttribute('aria-activedescendant');
+		}
+
+		this.view.domNode.setAttribute('role', 'tree');
+		DOM.toggleClass(this.view.domNode, 'element-focused', focus.length > 0);
 	}
 
 	dispose(): void {

src/vs/workbench/parts/extensions/browser/extensionsList.ts

@@ -23,6 +23,7 @@ import { IContextMenuService } from 'vs/platform/contextview/browser/contextView
 import { IExtensionService } from 'vs/platform/extensions/common/extensions';
 
 export interface ITemplateData {
+	root: HTMLElement;
 	element: HTMLElement;
 	icon: HTMLImageElement;
 	name: HTMLElement;
@@ -92,7 +93,7 @@ export class Renderer implements IPagedRenderer<IExtension, ITemplateData> {
 		const disposables = [versionWidget, installCountWidget, ratingsWidget, builtinStatusAction, updateAction, reloadAction, manageAction, actionbar];
 
 		return {
-			element, icon, name, installCount, ratings, author, description, disposables,
+			root, element, icon, name, installCount, ratings, author, description, disposables,
 			extensionDisposables: [],
 			set extension(extension: IExtension) {
 				versionWidget.extension = extension;
@@ -110,6 +111,7 @@ export class Renderer implements IPagedRenderer<IExtension, ITemplateData> {
 	renderPlaceholder(index: number, data: ITemplateData): void {
 		addClass(data.element, 'loading');
 
+		data.root.removeAttribute('aria-label');
 		data.extensionDisposables = dispose(data.extensionDisposables);
 		data.icon.src = '';
 		data.name.textContent = '';
@@ -142,6 +144,7 @@ export class Renderer implements IPagedRenderer<IExtension, ITemplateData> {
 			data.icon.style.visibility = 'inherit';
 		}
 
+		data.root.setAttribute('aria-label', extension.displayName);
 		data.name.textContent = extension.displayName;
 		data.author.textContent = extension.publisherDisplayName;
 		data.description.textContent = extension.description;

src/vs/workbench/parts/extensions/electron-browser/extensionsViewlet.ts

@@ -102,7 +102,9 @@ export class ExtensionsViewlet extends Viewlet implements IExtensionsViewlet {
 
 		const delegate = new Delegate();
 		const renderer = this.instantiationService.createInstance(Renderer);
-		this.list = new PagedList(this.extensionsBox, delegate, [renderer]);
+		this.list = new PagedList(this.extensionsBox, delegate, [renderer], {
+			ariaLabel: localize('extensions', "Extensions")
+		});
 
 		const onKeyDown = chain(domEvent(this.searchBox, 'keydown'))
 			.map(e => new StandardKeyboardEvent(e));
@@ -434,7 +436,7 @@ export class StatusUpdater implements IWorkbenchContribution {
 
 	private onServiceChange(): void {
 		if (this.extensionsWorkbenchService.local.some(e => e.state === ExtensionState.Installing)) {
-			this.activityBarService.showActivity(VIEWLET_ID, new ProgressBadge(() => localize('extensions', 'Extensions')), 'extensions-badge progress-badge');
+			this.activityBarService.showActivity(VIEWLET_ID, new ProgressBadge(() => localize('extensions', "Extensions")), 'extensions-badge progress-badge');
 			return;
 		}