fix(desktop): let the Theme Studio popout resolve its runtime (#3272)

fluxer_desktop/src/main/LocalAppTestSupport.test.mjs

@@ -78,7 +78,7 @@ const DESKTOP_APP_STORAGE_STUB = dataModule(`const state = globalThis[${JSON.str
 export const getDesktopAppStorage = () => state.desktopAppStorage;`);
 
 const WINDOW_STUB = dataModule(`const state = globalThis[${JSON.stringify(LIVE_STATE_KEY)}];
-export const getMainWindow = () => state.mainWindow;
+export const isAppDocumentWindowContents = (contents) => state.mainWindow?.webContents === contents;
 export const isTrustedOrigin = () => true;`);
 
 const APP_LOGGER_STUB = dataModule(`const noop = () => undefined;

fluxer_desktop/src/main/PrivilegedRendererDocuments.ts

@@ -3,7 +3,7 @@
 import {DESKTOP_APP_ORIGIN} from '@electron/common/Constants';
 import {createChildLogger} from '@electron/common/Logger';
 import {RendererDocumentOwnerFactory} from '@electron/main/RendererDocumentOwner';
-import {getMainWindow, isTrustedOrigin} from '@electron/main/Window';
+import {isAppDocumentWindowContents, isTrustedOrigin} from '@electron/main/Window';
 import type {IpcMainInvokeEvent} from 'electron';
 
 const BLANK_DOCUMENT_URL = 'about:blank';
@@ -49,7 +49,7 @@ export function createPrivilegedRendererDocumentOwners(componentName: string): R
 	const log = createChildLogger(componentName);
 	return new RendererDocumentOwnerFactory({
 		policy: {
-			isPrivilegedRendererDocument: ({sender, url}) => sender === getMainWindow()?.webContents && isTrustedOrigin(url),
+			isPrivilegedRendererDocument: ({sender, url}) => isAppDocumentWindowContents(sender) && isTrustedOrigin(url),
 		},
 		onWatcherFailure: (error, reason) => {
 			log.warn('Renderer document invalidation handling failed', {reason, error});

fluxer_desktop/src/main/Window.ts

@@ -364,6 +364,12 @@ function recoverMainWindowRendererBeforeShow(reason: string): void {
 	reloadMainWindowRendererAfterGone(reason);
 }
 
+export function isAppDocumentWindowContents(contents: Electron.WebContents): boolean {
+	return [mainWindow, themeStudioPopoutWindow].some(
+		(window) => isAliveWindow(window) && window.webContents === contents,
+	);
+}
+
 function getThemeStudioPopoutWindow(): BrowserWindow | null {
 	if (isAliveWindow(themeStudioPopoutWindow)) {
 		return themeStudioPopoutWindow;