Mark list event objects as readonly

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

@@ -24,40 +24,40 @@ export interface IListRenderer<T, TTemplateData> {
 }
 
 export interface IListEvent<T> {
-	elements: T[];
-	indexes: number[];
-	browserEvent?: UIEvent;
+	readonly elements: readonly T[];
+	readonly indexes: readonly number[];
+	readonly browserEvent?: UIEvent;
 }
 
 export interface IListMouseEvent<T> {
-	browserEvent: MouseEvent;
-	element: T | undefined;
-	index: number | undefined;
+	readonly browserEvent: MouseEvent;
+	readonly element: T | undefined;
+	readonly index: number | undefined;
 }
 
 export interface IListTouchEvent<T> {
-	browserEvent: TouchEvent;
-	element: T | undefined;
-	index: number | undefined;
+	readonly browserEvent: TouchEvent;
+	readonly element: T | undefined;
+	readonly index: number | undefined;
 }
 
 export interface IListGestureEvent<T> {
-	browserEvent: GestureEvent;
-	element: T | undefined;
-	index: number | undefined;
+	readonly browserEvent: GestureEvent;
+	readonly element: T | undefined;
+	readonly index: number | undefined;
 }
 
 export interface IListDragEvent<T> {
-	browserEvent: DragEvent;
-	element: T | undefined;
-	index: number | undefined;
+	readonly browserEvent: DragEvent;
+	readonly element: T | undefined;
+	readonly index: number | undefined;
 }
 
 export interface IListContextMenuEvent<T> {
-	browserEvent: UIEvent;
-	element: T | undefined;
-	index: number | undefined;
-	anchor: HTMLElement | { x: number; y: number };
+	readonly browserEvent: UIEvent;
+	readonly element: T | undefined;
+	readonly index: number | undefined;
+	readonly anchor: HTMLElement | { readonly x: number; readonly y: number };
 }
 
 export interface IIdentityProvider<T> {

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

@@ -134,8 +134,8 @@ export interface ITreeRenderer<T, TFilterData = void, TTemplateData = void> exte
 }
 
 export interface ITreeEvent<T> {
-	elements: T[];
-	browserEvent?: UIEvent;
+	readonly elements: readonly T[];
+	readonly browserEvent?: UIEvent;
 }
 
 export enum TreeMouseEventTarget {
@@ -146,15 +146,15 @@ export enum TreeMouseEventTarget {
 }
 
 export interface ITreeMouseEvent<T> {
-	browserEvent: MouseEvent;
-	element: T | null;
-	target: TreeMouseEventTarget;
+	readonly browserEvent: MouseEvent;
+	readonly element: T | null;
+	readonly target: TreeMouseEventTarget;
 }
 
 export interface ITreeContextMenuEvent<T> {
-	browserEvent: UIEvent;
-	element: T | null;
-	anchor: HTMLElement | { x: number; y: number };
+	readonly browserEvent: UIEvent;
+	readonly element: T | null;
+	readonly anchor: HTMLElement | { readonly x: number; readonly y: number };
 }
 
 export interface ITreeNavigator<T> {

src/vs/workbench/browser/parts/views/treeView.ts

@@ -219,8 +219,8 @@ abstract class AbstractTreeView extends Disposable implements ITreeView {
 	private readonly _onDidCollapseItem: Emitter<ITreeItem> = this._register(new Emitter<ITreeItem>());
 	readonly onDidCollapseItem: Event<ITreeItem> = this._onDidCollapseItem.event;
 
-	private _onDidChangeSelection: Emitter<ITreeItem[]> = this._register(new Emitter<ITreeItem[]>());
-	readonly onDidChangeSelection: Event<ITreeItem[]> = this._onDidChangeSelection.event;
+	private _onDidChangeSelection: Emitter<readonly ITreeItem[]> = this._register(new Emitter<readonly ITreeItem[]>());
+	readonly onDidChangeSelection: Event<readonly ITreeItem[]> = this._onDidChangeSelection.event;
 
 	private _onDidChangeFocus: Emitter<ITreeItem> = this._register(new Emitter<ITreeItem>());
 	readonly onDidChangeFocus: Event<ITreeItem> = this._onDidChangeFocus.event;
@@ -240,8 +240,8 @@ abstract class AbstractTreeView extends Disposable implements ITreeView {
 	private readonly _onDidChangeDescription: Emitter<string | undefined> = this._register(new Emitter<string | undefined>());
 	readonly onDidChangeDescription: Event<string | undefined> = this._onDidChangeDescription.event;
 
-	private readonly _onDidChangeCheckboxState: Emitter<ITreeItem[]> = this._register(new Emitter<ITreeItem[]>());
-	readonly onDidChangeCheckboxState: Event<ITreeItem[]> = this._onDidChangeCheckboxState.event;
+	private readonly _onDidChangeCheckboxState: Emitter<readonly ITreeItem[]> = this._register(new Emitter<readonly ITreeItem[]>());
+	readonly onDidChangeCheckboxState: Event<readonly ITreeItem[]> = this._onDidChangeCheckboxState.event;
 
 	private readonly _onDidCompleteRefresh: Emitter<void> = this._register(new Emitter<void>());
 
@@ -856,7 +856,7 @@ abstract class AbstractTreeView extends Disposable implements ITreeView {
 		return 0;
 	}
 
-	async refresh(elements?: ITreeItem[]): Promise<void> {
+	async refresh(elements?: readonly ITreeItem[]): Promise<void> {
 		if (this.dataProvider && this.tree) {
 			if (this.refreshing) {
 				await Event.toPromise(this._onDidCompleteRefresh.event);
@@ -930,7 +930,7 @@ abstract class AbstractTreeView extends Disposable implements ITreeView {
 	}
 
 	private refreshing: boolean = false;
-	private async doRefresh(elements: ITreeItem[]): Promise<void> {
+	private async doRefresh(elements: readonly ITreeItem[]): Promise<void> {
 		const tree = this.tree;
 		if (tree && this.visible) {
 			this.refreshing = true;

src/vs/workbench/common/views.ts

@@ -665,7 +665,7 @@ export interface ITreeView extends IDisposable {
 
 	readonly onDidCollapseItem: Event<ITreeItem>;
 
-	readonly onDidChangeSelection: Event<ITreeItem[]>;
+	readonly onDidChangeSelection: Event<readonly ITreeItem[]>;
 
 	readonly onDidChangeFocus: Event<ITreeItem>;
 
@@ -679,11 +679,11 @@ export interface ITreeView extends IDisposable {
 
 	readonly onDidChangeWelcomeState: Event<void>;
 
-	readonly onDidChangeCheckboxState: Event<ITreeItem[]>;
+	readonly onDidChangeCheckboxState: Event<readonly ITreeItem[]>;
 
 	readonly container: any | undefined;
 
-	refresh(treeItems?: ITreeItem[]): Promise<void>;
+	refresh(treeItems?: readonly ITreeItem[]): Promise<void>;
 
 	setVisibility(visible: boolean): void;
 

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

@@ -600,7 +600,7 @@ export class ExplorerView extends ViewPane implements IExplorerView {
 		});
 	}
 
-	private onFocusChanged(elements: ExplorerItem[]): void {
+	private onFocusChanged(elements: readonly ExplorerItem[]): void {
 		const stat = elements && elements.length ? elements[0] : undefined;
 		this.setContextKeys(stat);
 

src/vs/workbench/contrib/notebook/browser/view/notebookCellList.ts

@@ -88,7 +88,7 @@ export class NotebookCellList extends WorkbenchList<CellViewModel> implements ID
 	get scrollableElement(): HTMLElement {
 		return this.view.scrollableElementDomNode;
 	}
-	private _previousFocusedElements: CellViewModel[] = [];
+	private _previousFocusedElements: readonly CellViewModel[] = [];
 	private readonly _localDisposableStore = new DisposableStore();
 	private readonly _viewModelStore = new DisposableStore();
 	private styleElement?: HTMLStyleElement;

src/vs/workbench/contrib/remote/browser/tunnelView.ts

@@ -949,7 +949,7 @@ export class TunnelPanel extends ViewPane {
 
 	private onFocusChanged(event: ITableEvent<ITunnelItem>) {
 		if (event.indexes.length > 0 && event.elements.length > 0) {
-			this.lastFocus = event.indexes;
+			this.lastFocus = [...event.indexes];
 		}
 		const elements = event.elements;
 		const item = elements && elements.length ? elements[0] : undefined;

src/vs/workbench/contrib/scm/common/scm.ts

@@ -197,7 +197,7 @@ export interface ISCMViewService {
 	repositories: ISCMRepository[];
 	readonly onDidChangeRepositories: Event<ISCMViewVisibleRepositoryChangeEvent>;
 
-	visibleRepositories: ISCMRepository[];
+	visibleRepositories: readonly ISCMRepository[];
 	readonly onDidChangeVisibleRepositories: Event<ISCMViewVisibleRepositoryChangeEvent>;
 
 	isVisible(repository: ISCMRepository): boolean;

src/vs/workbench/services/userDataProfile/browser/userDataProfileImportExportService.ts

@@ -873,7 +873,7 @@ abstract class UserDataProfileImportExportState extends Disposable implements IT
 		}
 	}
 
-	onDidChangeCheckboxState(items: ITreeItem[]): ITreeItem[] {
+	onDidChangeCheckboxState(items: readonly ITreeItem[]): readonly ITreeItem[] {
 		const toRefresh: ITreeItem[] = [];
 		for (const item of items) {
 			if (item.children) {