fix: MacOS 26 Tahoe - stop overriding private cornerMask API to fix WindowServer GPU load (electron#48376)

avarayr · web-flow · commit 3a7c6dd4a551 · 2025-09-26T12:41:16.000-07:00
fix: macOS stop overriding private cornerMask API to fix WindowServer GPU load spike

Electron fetched a custom `_cornerMask` for `ElectronNSWindow` to smooth
vibrancy corners. On macOS 15 (Tahoe) that private hook forces the window
shadow to be rendered from a fully transparent surface, causing the
WindowServer GPU load regression. Remove the `cornerMask` property and
the `_cornerMask` override so we stay on Apple’s default shadow path.
diff --git a/shell/browser/native_window_mac.mm b/shell/browser/native_window_mac.mm
@@ -1333,7 +1333,6 @@ static bool FromV8(v8::Isolate* isolate,
       maskImage.capInsets = NSEdgeInsetsMake(radius, radius, radius, radius);
       maskImage.resizingMode = NSImageResizingModeStretch;
       [vibrantView setMaskImage:maskImage];
-      [window_ setCornerMask:maskImage];
     }
   }
 }
diff --git a/shell/browser/ui/cocoa/electron_ns_window.h b/shell/browser/ui/cocoa/electron_ns_window.h
@@ -40,15 +40,13 @@ class ElectronNativeWindowObserver;
 @property BOOL disableAutoHideCursor;
 @property BOOL disableKeyOrMainWindow;
 @property(nonatomic, retain) NSVisualEffectView* vibrantView;
-@property(nonatomic, retain) NSImage* cornerMask;
 - (id)initWithShell:(electron::NativeWindowMac*)shell
           styleMask:(NSUInteger)styleMask;
 - (void)cleanup;
 - (electron::NativeWindowMac*)shell;
 - (id)accessibilityFocusedUIElement;
 - (NSRect)originalContentRectForFrameRect:(NSRect)frameRect;
 - (BOOL)toggleFullScreenMode:(id)sender;
-- (NSImage*)_cornerMask;
 - (void)disableHeadlessMode;
 @end
 
diff --git a/shell/browser/ui/cocoa/electron_ns_window.mm b/shell/browser/ui/cocoa/electron_ns_window.mm
@@ -25,7 +25,6 @@
 }  // namespace electron
 
 @interface NSWindow (PrivateAPI)
-- (NSImage*)_cornerMask;
 - (int64_t)_resizeDirectionForMouseLocation:(CGPoint)location;
 @end
 
@@ -123,7 +122,6 @@ @implementation ElectronNSWindow
 @synthesize disableAutoHideCursor;
 @synthesize disableKeyOrMainWindow;
 @synthesize vibrantView;
-@synthesize cornerMask;
 
 - (id)initWithShell:(electron::NativeWindowMac*)shell
           styleMask:(NSUInteger)styleMask {
@@ -308,16 +306,6 @@ - (BOOL)validateUserInterfaceItem:(id<NSValidatedUserInterfaceItem>)item {
   return [super validateUserInterfaceItem:item];
 }
 
-// By overriding this built-in method the corners of the vibrant view (if set)
-// will be smooth.
-- (NSImage*)_cornerMask {
-  if (self.vibrantView != nil) {
-    return [self cornerMask];
-  } else {
-    return [super _cornerMask];
-  }
-}
-
 - (void)disableHeadlessMode {
   if (shell_) {
     // We initialize the window in headless mode to allow painting before it is

Original file line number	Diff line number	Diff line change
`@@ -1333,7 +1333,6 @@ static bool FromV8(v8::Isolate* isolate,`
`1333`	`1333`	`maskImage.capInsets = NSEdgeInsetsMake(radius, radius, radius, radius);`
`1334`	`1334`	`maskImage.resizingMode = NSImageResizingModeStretch;`
`1335`	`1335`	`[vibrantView setMaskImage:maskImage];`
`1336`		`- [window_ setCornerMask:maskImage];`
`1337`	`1336`	`}`
`1338`	`1337`	`}`
`1339`	`1338`	`}`