Fix retainContextWhileHidden

Fixes #52073

src/vs/base/common/arrays.ts

@@ -24,7 +24,7 @@ export function tail2<T>(arr: T[]): [T[], T] {
 	return [arr.slice(0, arr.length - 1), arr[arr.length - 1]];
 }
 
-export function equals<T>(one: T[], other: T[], itemEquals: (a: T, b: T) => boolean = (a, b) => a === b): boolean {
+export function equals<T>(one: ReadonlyArray<T>, other: ReadonlyArray<T>, itemEquals: (a: T, b: T) => boolean = (a, b) => a === b): boolean {
 	if (one.length !== other.length) {
 		return false;
 	}

src/vs/workbench/parts/webview/electron-browser/webviewEditorService.ts

@@ -12,6 +12,7 @@ import { IEditorGroupsService, IEditorGroup } from 'vs/workbench/services/group/
 import * as vscode from 'vscode';
 import { WebviewEditorInput } from './webviewEditorInput';
 import { GroupIdentifier } from 'vs/workbench/common/editor';
+import { equals } from 'vs/base/common/arrays';
 
 export const IWebviewEditorService = createDecorator<IWebviewEditorService>('webviewEditorService');
 
@@ -76,6 +77,15 @@ export interface WebviewInputOptions extends vscode.WebviewOptions, vscode.Webvi
 	tryRestoreScrollPosition?: boolean;
 }
 
+export function areWebviewInputOptionsEqual(a: WebviewInputOptions, b: WebviewInputOptions): boolean {
+	return a.enableCommandUris === b.enableCommandUris
+		&& a.enableFindWidget === b.enableFindWidget
+		&& a.enableScripts === b.enableScripts
+		&& a.retainContextWhenHidden === b.retainContextWhenHidden
+		&& a.tryRestoreScrollPosition === b.tryRestoreScrollPosition
+		&& (a.localResourceRoots === b.localResourceRoots || (Array.isArray(a.localResourceRoots) && Array.isArray(b.localResourceRoots) && equals(a.localResourceRoots, b.localResourceRoots, (a, b) => a.toString() === b.toString())));
+}
+
 export class WebviewEditorService implements IWebviewEditorService {
 	_serviceBrand: any;
 

src/vs/workbench/parts/webview/electron-browser/webviewElement.ts

@@ -17,6 +17,7 @@ import { IInstantiationService } from 'vs/platform/instantiation/common/instanti
 import * as colorRegistry from 'vs/platform/theme/common/colorRegistry';
 import { DARK, ITheme, IThemeService, LIGHT } from 'vs/platform/theme/common/themeService';
 import { WebviewFindWidget } from './webviewFindWidget';
+import { areWebviewInputOptionsEqual } from './webviewEditorService';
 
 export interface WebviewOptions {
 	readonly allowScripts?: boolean;
@@ -255,6 +256,10 @@ export class WebviewElement extends Disposable {
 	}
 
 	public set options(value: WebviewOptions) {
+		if (this._options && areWebviewInputOptionsEqual(value, this._options)) {
+			return;
+		}
+
 		this._options = value;
 		this._send('content', {
 			contents: this._contents,