fix: provide correct container and make sure containerElement is never null

Author: gaspar-chefdeville

src/service-override/workbench.ts

@@ -59,10 +59,10 @@ class CustomWorkbench extends Workbench {
   }
 }
 
-const detectedFullScreen = detectFullscreen(mainWindow)
-setFullscreen(detectedFullScreen != null && !detectedFullScreen.guess, mainWindow)
 onLayout(async (accessor) => {
   ;(accessor.get(IWorkbenchLayoutService) as Workbench).startup()
+  const detectedFullScreen = detectFullscreen(mainWindow, getWorkbenchContainer())
+  setFullscreen(detectedFullScreen != null && !detectedFullScreen.guess, mainWindow)
 })
 onRenderWorkbench(async (accessor) => {
   accessor.get(IInstantiationService).createInstance(BrowserWindow)

vscode-patches/0072-fix-provide-correct-container-and-check-if-fullscree.patch

@@ -0,0 +1,56 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Gaspar Chefdeville <gaspar.chefdeville@coderpad.io>
+Date: Wed, 9 Jul 2025 17:07:58 +0200
+Subject: [PATCH] fix: provide correct container and check if fullscreen
+
+---
+ src/vs/base/browser/dom.ts                                | 8 +++++---
+ .../workbench/services/host/browser/browserHostService.ts | 2 +-
+ 2 files changed, 6 insertions(+), 4 deletions(-)
+
+diff --git a/src/vs/base/browser/dom.ts b/src/vs/base/browser/dom.ts
+index 44afc1906a7..af89a7f1e46 100644
+--- a/src/vs/base/browser/dom.ts
++++ b/src/vs/base/browser/dom.ts
+@@ -1626,7 +1626,7 @@ export interface IDetectedFullscreen {
+ 	guess: boolean;
+ }
+ 
+-export function detectFullscreen(targetWindow: Window, containerElement?: Element): IDetectedFullscreen | null {
++export function detectFullscreen(targetWindow: Window, containerElement: Element): IDetectedFullscreen | null {
+ 
+ 	// Browser fullscreen: use DOM APIs to detect
+ 	const fullscreenElement: Element | undefined =
+@@ -1640,7 +1640,9 @@ export function detectFullscreen(targetWindow: Window, containerElement?: Elemen
+ 	// height and comparing that to window height, we can guess
+ 	// it though.
+ 
+-	if (targetWindow.innerHeight === targetWindow.screen.height) {
++	const isContainerFullScreen = containerElement.getBoundingClientRect().height >= targetWindow.screen.height;
++
++	if (targetWindow.innerHeight === targetWindow.screen.height && isContainerFullScreen) {
+ 		// if the height of the window matches the screen height, we can
+ 		// safely assume that the browser is fullscreen because no browser
+ 		// chrome is taking height away (e.g. like toolbars).
+@@ -1649,7 +1651,7 @@ export function detectFullscreen(targetWindow: Window, containerElement?: Elemen
+ 
+ 	if (platform.isMacintosh || platform.isLinux) {
+ 		// macOS and Linux do not properly report `innerHeight`, only Windows does
+-		if (targetWindow.outerHeight === targetWindow.screen.height && targetWindow.outerWidth === targetWindow.screen.width) {
++		if (targetWindow.outerHeight === targetWindow.screen.height && targetWindow.outerWidth === targetWindow.screen.width && isContainerFullScreen) {
+ 			// if the height of the browser matches the screen height, we can
+ 			// only guess that we are in fullscreen. It is also possible that
+ 			// the user has turned off taskbars in the OS and the browser is
+diff --git a/src/vs/workbench/services/host/browser/browserHostService.ts b/src/vs/workbench/services/host/browser/browserHostService.ts
+index 851a4cfad41..6e41a554052 100644
+--- a/src/vs/workbench/services/host/browser/browserHostService.ts
++++ b/src/vs/workbench/services/host/browser/browserHostService.ts
+@@ -218,7 +218,7 @@ export class BrowserHostService extends Disposable implements IHostService {
+ 			const viewport = isIOS && window.visualViewport ? window.visualViewport /** Visual viewport */ : window /** Layout viewport */;
+ 
+ 			const isFullScreen = () => {
+-				const fullScreen = detectFullscreen(window, mainWindow.document.body);
++				const fullScreen = detectFullscreen(window, this.layoutService.getContainer(window));
+ 				return fullScreen !== null && !fullScreen.guess;
+ 			};
+