fixes #40261

src/vs/platform/list/browser/listService.ts

@@ -73,12 +73,18 @@ export class ListService implements IListService {
 }
 
 const RawWorkbenchListFocusContextKey = new RawContextKey<boolean>('listFocus', true);
+export const WorkbenchListSupportsMultiSelectContextKey = new RawContextKey<boolean>('listSupportsMultiselect', true);
 export const WorkbenchListFocusContextKey = ContextKeyExpr.and(RawWorkbenchListFocusContextKey, ContextKeyExpr.not(InputFocusedContextKey));
 
 export type Widget = List<any> | PagedList<any> | ITree;
 
 function createScopedContextKeyService(contextKeyService: IContextKeyService, widget: Widget): IContextKeyService {
 	const result = contextKeyService.createScoped(widget.getHTMLElement());
+
+	if (widget instanceof List || widget instanceof PagedList) {
+		WorkbenchListSupportsMultiSelectContextKey.bindTo(result);
+	}
+
 	RawWorkbenchListFocusContextKey.bindTo(result);
 	return result;
 }

src/vs/workbench/electron-browser/commands.ts

@@ -19,9 +19,10 @@ import { IWorkbenchEditorService } from 'vs/workbench/services/editor/common/edi
 import URI from 'vs/base/common/uri';
 import { IEditorOptions, Position as EditorPosition } from 'vs/platform/editor/common/editor';
 import { openFolderCommand, openFileInNewWindowCommand, openFileFolderInNewWindowCommand, openFolderInNewWindowCommand, openWorkspaceInNewWindowCommand } from 'vs/workbench/browser/actions/workspaceActions';
-import { WorkbenchListFocusContextKey, IListService } from 'vs/platform/list/browser/listService';
+import { WorkbenchListFocusContextKey, IListService, WorkbenchListSupportsMultiSelectContextKey } from 'vs/platform/list/browser/listService';
 import { PagedList } from 'vs/base/browser/ui/list/listPaging';
 import { range } from 'vs/base/common/arrays';
+import { ContextKeyExpr } from 'vs/platform/contextkey/common/contextkey';
 
 // --- List Commands
 
@@ -304,7 +305,7 @@ export function registerCommands(): void {
 	KeybindingsRegistry.registerCommandAndKeybindingRule({
 		id: 'list.selectAll',
 		weight: KeybindingsRegistry.WEIGHT.workbenchContrib(),
-		when: WorkbenchListFocusContextKey,
+		when: ContextKeyExpr.and(WorkbenchListFocusContextKey, WorkbenchListSupportsMultiSelectContextKey),
 		primary: KeyMod.CtrlCmd | KeyCode.KEY_A,
 		handler: (accessor) => {
 			const focused = accessor.get(IListService).lastFocusedList;