explorer: improve aria-level computation of compact folders

#107235

src/vs/base/browser/ui/tree/abstractTree.ts

@@ -186,7 +186,7 @@ function asListOptions<T, TFilterData, TRef>(modelProvider: () => ITreeModel<T,
 				return options.accessibilityProvider!.getWidgetAriaLabel();
 			},
 			getWidgetRole: options.accessibilityProvider && options.accessibilityProvider.getWidgetRole ? () => options.accessibilityProvider!.getWidgetRole!() : () => 'tree',
-			getAriaLevel(node) {
+			getAriaLevel: options.accessibilityProvider && options.accessibilityProvider.getAriaLevel ? (node) => options.accessibilityProvider!.getAriaLevel!(node.element) : (node) => {
 				return node.depth;
 			},
 			getActiveDescendantId: options.accessibilityProvider.getActiveDescendantId && (node => {

src/vs/workbench/contrib/files/browser/views/explorerViewer.ts

@@ -255,7 +255,8 @@ export class FilesRenderer implements ICompressibleTreeRenderer<ExplorerItem, Fu
 		@IThemeService private readonly themeService: IThemeService,
 		@IConfigurationService private readonly configurationService: IConfigurationService,
 		@IExplorerService private readonly explorerService: IExplorerService,
-		@ILabelService private readonly labelService: ILabelService
+		@ILabelService private readonly labelService: ILabelService,
+		@IWorkspaceContextService private readonly contextService: IWorkspaceContextService
 	) {
 		this.config = this.configurationService.getValue<IFilesConfiguration>();
 		this.configListener = this.configurationService.onDidChangeConfiguration(e => {
@@ -491,6 +492,22 @@ export class FilesRenderer implements ICompressibleTreeRenderer<ExplorerItem, Fu
 		return element.name;
 	}
 
+	getAriaLevel(element: ExplorerItem): number {
+		// We need to comput aria level on our own since children of compact folders will otherwise have an incorrect level	#107235
+		let depth = 0;
+		let parent = element.parent;
+		while (parent) {
+			parent = parent.parent;
+			depth++;
+		}
+
+		if (this.contextService.getWorkbenchState() === WorkbenchState.WORKSPACE) {
+			depth = depth + 1;
+		}
+
+		return depth;
+	}
+
 	getActiveDescendantId(stat: ExplorerItem): string | undefined {
 		const compressedNavigationController = this.compressedNavigationControllers.get(stat);
 		return compressedNavigationController?.currentId;