fix: fullscreen for windows without rounded corners (#47681)

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Shelley Vohr <shelley.vohr@gmail.com>

shell/browser/native_window_mac.h

@@ -175,6 +175,8 @@ class NativeWindowMac : public NativeWindow,
   // cleanup in destructor.
   void Cleanup();
 
+  void SetBorderless(bool borderless);
+
   void UpdateVibrancyRadii(bool fullscreen);
 
   void UpdateWindowOriginalFrame();

shell/browser/native_window_mac.mm

@@ -154,13 +154,6 @@ NativeWindowMac::NativeWindowMac(const gin_helper::Dictionary& options,
 
   NSUInteger styleMask = NSWindowStyleMaskTitled;
 
-  // The NSWindowStyleMaskFullSizeContentView style removes rounded corners
-  // for frameless window.
-  const bool rounded_corner =
-      options.ValueOrDefault(options::kRoundedCorners, true);
-  if (!rounded_corner && !has_frame())
-    styleMask = NSWindowStyleMaskBorderless;
-
   if (minimizable)
     styleMask |= NSWindowStyleMaskMiniaturizable;
   if (closable)
@@ -220,6 +213,11 @@ NativeWindowMac::NativeWindowMac(const gin_helper::Dictionary& options,
     SetParentWindow(parent);
   }
 
+  const bool rounded_corner =
+      options.ValueOrDefault(options::kRoundedCorners, true);
+  if (!rounded_corner && !has_frame())
+    SetBorderless(!rounded_corner);
+
   if (transparent()) {
     // Setting the background color to clear will also hide the shadow.
     [window_ setBackgroundColor:[NSColor clearColor]];
@@ -768,6 +766,11 @@ void NativeWindowMac::MoveTop() {
   [window_ orderWindowByShuffling:NSWindowAbove relativeTo:0];
 }
 
+void NativeWindowMac::SetBorderless(bool borderless) {
+  SetStyleMask(!borderless, NSWindowStyleMaskTitled);
+  SetStyleMask(borderless, NSWindowStyleMaskBorderless);
+}
+
 void NativeWindowMac::SetResizable(bool resizable) {
   ScopedDisableResize disable_resize;
   SetStyleMask(resizable, NSWindowStyleMaskResizable);

shell/browser/ui/cocoa/electron_ns_window.mm

@@ -375,9 +375,6 @@ void SwizzleSwipeWithEvent(NSView* view, SEL swiz_selector) {
 }
 
 - (BOOL)toggleFullScreenMode:(id)sender {
-  if (!shell_->has_frame() && !shell_->HasStyleMask(NSWindowStyleMaskTitled))
-    return NO;
-
   bool is_simple_fs = shell_->IsSimpleFullScreen();
   bool always_simple_fs = shell_->always_simple_fullscreen();
 

shell/browser/ui/cocoa/electron_ns_window_delegate.h

@@ -24,6 +24,8 @@ class NativeWindowMac;
   int level_;
   bool is_resizable_;
 
+  bool is_borderless_;
+
   // Whether the window is currently minimized. Used to work
   // around a macOS bug with child window minimization.
   bool is_minimized_;

shell/browser/ui/cocoa/electron_ns_window_delegate.mm

@@ -299,6 +299,8 @@ using TitleBarStyle = electron::NativeWindowMac::TitleBarStyle;
 - (void)windowWillEnterFullScreen:(NSNotification*)notification {
   // Store resizable mask so it can be restored after exiting fullscreen.
   is_resizable_ = shell_->HasStyleMask(NSWindowStyleMaskResizable);
+  // Store borderless mask so it can be restored after exiting fullscreen.
+  is_borderless_ = !shell_->HasStyleMask(NSWindowStyleMaskTitled);
 
   shell_->set_is_transitioning_fullscreen(true);
 
@@ -306,6 +308,8 @@ using TitleBarStyle = electron::NativeWindowMac::TitleBarStyle;
 
   // Set resizable to true before entering fullscreen.
   shell_->SetResizable(true);
+  // Set borderless to false before entering fullscreen.
+  shell_->SetBorderless(false);
 }
 
 - (void)windowDidEnterFullScreen:(NSNotification*)notification {
@@ -341,6 +345,7 @@ using TitleBarStyle = electron::NativeWindowMac::TitleBarStyle;
   shell_->set_is_transitioning_fullscreen(false);
 
   shell_->SetResizable(is_resizable_);
+  shell_->SetBorderless(is_borderless_);
   shell_->NotifyWindowLeaveFullScreen();
 
   if (shell_->HandleDeferredClose())

spec/api-browser-window-spec.ts

@@ -6030,6 +6030,54 @@ describe('BrowserWindow module', () => {
         await leaveFullScreen;
       });
 
+      it('should not crash if rounded corners are disabled', async () => {
+        const w = new BrowserWindow({
+          frame: false,
+          roundedCorners: false
+        });
+
+        const enterFullScreen = once(w, 'enter-full-screen');
+        w.setFullScreen(true);
+        await enterFullScreen;
+
+        await setTimeout();
+
+        const leaveFullScreen = once(w, 'leave-full-screen');
+        w.setFullScreen(false);
+        await leaveFullScreen;
+      });
+
+      it('should not crash if opening a borderless child window from fullscreen parent', async () => {
+        const parent = new BrowserWindow();
+
+        const parentFS = once(parent, 'enter-full-screen');
+        parent.setFullScreen(true);
+        await parentFS;
+
+        await setTimeout();
+
+        const child = new BrowserWindow({
+          width: 400,
+          height: 300,
+          show: false,
+          parent,
+          frame: false,
+          roundedCorners: false
+        });
+
+        await setTimeout();
+
+        const childFS = once(child, 'enter-full-screen');
+        child.show();
+        await childFS;
+
+        await setTimeout();
+
+        const leaveFullScreen = once(child, 'leave-full-screen');
+        child.setFullScreen(false);
+        await leaveFullScreen;
+      });
+
       it('should be able to load a URL while transitioning to fullscreen', async () => {
         const w = new BrowserWindow({ fullscreen: true });
         w.loadFile(path.join(fixtures, 'pages', 'c.html'));