Fix #97125

src/vs/base/browser/ui/dropdown/dropdown.ts

@@ -14,6 +14,7 @@ import { ResolvedKeybinding, KeyCode } from 'vs/base/common/keyCodes';
 import { EventHelper, EventType, removeClass, addClass, append, $, addDisposableListener, addClasses } from 'vs/base/browser/dom';
 import { IContextMenuDelegate } from 'vs/base/browser/contextmenu';
 import { StandardKeyboardEvent } from 'vs/base/browser/keyboardEvent';
+import { Emitter } from 'vs/base/common/event';
 
 export interface ILabelRenderer {
 	(container: HTMLElement): IDisposable | null;
@@ -29,7 +30,10 @@ export class BaseDropdown extends ActionRunner {
 	private boxContainer?: HTMLElement;
 	private _label?: HTMLElement;
 	private contents?: HTMLElement;
+
 	private visible: boolean | undefined;
+	private _onDidChangeVisibility = new Emitter<boolean>();
+	readonly onDidChangeVisibility = this._onDidChangeVisibility.event;
 
 	constructor(container: HTMLElement, options: IBaseDropdownOptions) {
 		super();
@@ -101,11 +105,17 @@ export class BaseDropdown extends ActionRunner {
 	}
 
 	show(): void {
-		this.visible = true;
+		if (!this.visible) {
+			this.visible = true;
+			this._onDidChangeVisibility.fire(true);
+		}
 	}
 
 	hide(): void {
-		this.visible = false;
+		if (this.visible) {
+			this.visible = false;
+			this._onDidChangeVisibility.fire(false);
+		}
 	}
 
 	isVisible(): boolean {
@@ -303,6 +313,7 @@ export class DropdownMenuActionViewItem extends BaseActionViewItem {
 			this.element.tabIndex = 0;
 			this.element.setAttribute('role', 'button');
 			this.element.setAttribute('aria-haspopup', 'true');
+			this.element.setAttribute('aria-expanded', 'false');
 			this.element.title = this._action.label || '';
 
 			return null;
@@ -321,6 +332,7 @@ export class DropdownMenuActionViewItem extends BaseActionViewItem {
 		}
 
 		this.dropdownMenu = this._register(new DropdownMenu(container, options));
+		this._register(this.dropdownMenu.onDidChangeVisibility(visible => this.element?.setAttribute('aria-expanded', `${visible}`)));
 
 		this.dropdownMenu.menuOptions = {
 			actionViewItemProvider: this.actionViewItemProvider,