feat: hide menu bar on windows fullscreen (#43402)

* feat: hide menu bar on windows fullscreen

* test: state prior to html fullscreen transition

* refactor: restore `#ifdef` for readability

Reference: https://github.com/electron/electron/pull/43402#discussion_r1729356262

* docs: menu bar behavior changed

---------

Co-authored-by: John Kleinschmidt <jkleinsc@electronjs.org>

docs/breaking-changes.md

@@ -14,6 +14,10 @@ This document uses the following convention to categorize breaking changes:
 
 ## Planned Breaking API Changes (33.0)
 
+### Behavior Changed: menu bar will be hidden during fullscreen on Windows
+
+This brings the behavior to parity with Linux. Prior behavior: Menu bar is still visible during fullscreen on Windows. New behavior: Menu bar is hidden during fullscreen on Windows.
+
 ### Behavior Changed: `webContents` property on `login` on `app`
 
 The `webContents` property in the `login` event from `app` will be `null`

shell/browser/native_window_views.cc

@@ -746,6 +746,24 @@ void NativeWindowViews::SetFullScreen(bool fullscreen) {
   // Note: the following must be after "widget()->SetFullscreen(fullscreen);"
   if (leaving_fullscreen && !IsVisible())
     FlipWindowStyle(GetAcceleratedWidget(), true, WS_VISIBLE);
+
+  // Auto-hide menubar when in fullscreen.
+  if (fullscreen) {
+    menu_bar_visible_before_fullscreen_ = IsMenuBarVisible();
+    SetMenuBarVisibility(false);
+  } else {
+    // No fullscreen -> fullscreen video -> un-fullscreen video results
+    // in `NativeWindowViews::SetFullScreen(false)` being called twice.
+    // `menu_bar_visible_before_fullscreen_` is always false on the
+    //  second call which results in `SetMenuBarVisibility(false)` no
+    // matter what. We check `leaving_fullscreen` to avoid this.
+    if (!leaving_fullscreen)
+      return;
+
+    SetMenuBarVisibility(!IsMenuBarAutoHide() &&
+                         menu_bar_visible_before_fullscreen_);
+    menu_bar_visible_before_fullscreen_ = false;
+  }
 #else
   if (IsVisible())
     widget()->SetFullscreen(fullscreen);

spec/api-browser-window-spec.ts

@@ -5630,6 +5630,37 @@ describe('BrowserWindow module', () => {
       });
     });
 
+    ifdescribe(process.platform !== 'darwin')('fullscreen state', () => {
+      it('correctly remembers state prior to HTML fullscreen transition', async () => {
+        const w = new BrowserWindow();
+        await w.loadFile(path.join(fixtures, 'pages', 'a.html'));
+
+        expect(w.isMenuBarVisible()).to.be.true('isMenuBarVisible');
+        expect(w.isFullScreen()).to.be.false('is fullscreen');
+
+        const enterFullScreen = once(w, 'enter-full-screen');
+        const leaveFullScreen = once(w, 'leave-full-screen');
+
+        await w.webContents.executeJavaScript('document.getElementById("div").requestFullscreen()', true);
+        await enterFullScreen;
+        await w.webContents.executeJavaScript('document.exitFullscreen()', true);
+        await leaveFullScreen;
+
+        expect(w.isFullScreen()).to.be.false('is fullscreen');
+        expect(w.isMenuBarVisible()).to.be.true('isMenuBarVisible');
+
+        w.setMenuBarVisibility(false);
+        expect(w.isMenuBarVisible()).to.be.false('isMenuBarVisible');
+
+        await w.webContents.executeJavaScript('document.getElementById("div").requestFullscreen()', true);
+        await enterFullScreen;
+        await w.webContents.executeJavaScript('document.exitFullscreen()', true);
+        await leaveFullScreen;
+
+        expect(w.isMenuBarVisible()).to.be.false('isMenuBarVisible');
+      });
+    });
+
     ifdescribe(process.platform === 'darwin')('fullscreenable state', () => {
       it('with functions', () => {
         it('can be set with fullscreenable constructor option', () => {