list: improve aria-selected to be set on each selected element. Set...

list: improve aria-selected to be set on each selected element. Set aria-multiselectable when mutli selct is supported

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

@@ -180,10 +180,10 @@ class Trait<T> implements ISpliceable<boolean>, IDisposable {
 	}
 }
 
-class FocusTrait<T> extends Trait<T> {
+class SelectionTrait<T> extends Trait<T> {
 
 	constructor() {
-		super('focused');
+		super('selected');
 	}
 
 	renderIndex(index: number, container: HTMLElement): void {
@@ -1198,8 +1198,8 @@ export class List<T> implements ISpliceable<T>, IDisposable {
 		renderers: IListRenderer<any /* TODO@joao */, any>[],
 		private _options: IListOptions<T> = DefaultOptions
 	) {
-		this.focus = new FocusTrait();
-		this.selection = new Trait('selected');
+		this.focus = new Trait('focused');
+		this.selection = new SelectionTrait();
 
 		mixin(_options, defaultStyles, false);
 
@@ -1272,6 +1272,9 @@ export class List<T> implements ISpliceable<T>, IDisposable {
 		if (_options.ariaLabel) {
 			this.view.domNode.setAttribute('aria-label', localize('aria list', "{0}. Use the navigation keys to navigate.", _options.ariaLabel));
 		}
+		if (_options.multipleSelectionSupport) {
+			this.view.domNode.setAttribute('aria-multiselectable', 'true');
+		}
 	}
 
 	protected createMouseController(options: IListOptions<T>): MouseController<T> {

src/vs/base/parts/tree/browser/treeView.ts

@@ -218,13 +218,15 @@ export class ViewItem implements IViewItem {
 		}
 		if (this.model.hasTrait('focused')) {
 			const base64Id = strings.safeBtoa(this.model.id);
-
-			this.element.setAttribute('aria-selected', 'true');
 			this.element.setAttribute('id', base64Id);
 		} else {
-			this.element.setAttribute('aria-selected', 'false');
 			this.element.removeAttribute('id');
 		}
+		if (this.model.hasTrait('selected')) {
+			this.element.setAttribute('aria-selected', 'true');
+		} else {
+			this.element.setAttribute('aria-selected', 'false');
+		}
 		if (this.model.hasChildren()) {
 			this.element.setAttribute('aria-expanded', String(!!this._styles['expanded']));
 		} else {