I have a Mac application that uses the NSEvent.addLocalMonitorForEvents API to receive all mouse movement events. It receives all the mouse movement events and calculate the event reporting rate. The code used as following: import SwiftUI struct ContentView: View { var body: some View { VStack { Image(systemName: "globe") .imageScale(.large) .foregroundColor(.accentColor) Text("Hello, world!") } .frame(width: 400, height: 400) .padding() .onAppear() { // here NSEvent.addLocalMonitorForEvents(matching: [.mouseMoved]) { event in print(event.timestamp) return event } } } } With the exact same code, before I upgraded my macOS to the latest version 26.2, I could receive approximately 460+ mouse events per second, this matched the hardware reporting frequency of my mouse device perfectly. However, after upgrading to version 26.2, I noticed that the number of mouse events received per second is limited to match the screen refresh rate: when I set the screen refresh rate to 60Hz, I only receive 60 mouse events per second; when set to 120Hz, I receive 120 events per second. It is clear that some changes has be delivered in macOS 26.2, which by default downsamples the frequency of mouse events reported to applications to align with the screen refresh rate. The question is how can I reteive all the original mouse events in macOS 26.2? I tried to search and dig, bug no any related APIs found.

Hello, I am developing a macOS app using AudioToolbox's MusicSequence and MusicPlayer APIs to play Standard MIDI Files. The MIDI playback works correctly and I can hear sound from the external MIDI device. However, the user callback registered via MusicSequenceSetUserCallback is never invoked during playback. Details: Callback registration returns no error. MusicPlayer is properly started and prerolled. The callback is defined as a global function with the correct @convention(c) signature. I have tried commenting out MusicTrackSetDestMIDIEndpoint to avoid known callback suppression issues. The clientData pointer is passed and correctly unwrapped in the callback. Minimal reproducible example shows the same behavior. Environment: macOS version: [Tahoe 26.2] Xcode version: [26.2] Is it expected that MusicSequenceSetUserCallback callbacks may not be called in some cases? Are there additional steps or configurations required to ensure the callback is triggered during MIDI playback? Thank you for any advice or pointers. Execute playTest() in the viewDidLoad() method of the ViewController. extension ViewController { private func playTest() { NewMusicSequence(&sequence) if let midiFileURL = Bundle.main.url(forResource: "etude", withExtension: "mid") { MusicSequenceFileLoad(sequence!, midiFileURL as CFURL, .midiType,MusicSequenceLoadFlags()) NewMusicPlayer(&player) MusicPlayerSetSequence(player!, sequence!) MusicPlayerPreroll(player!) let status = MusicSequenceSetUserCallback(sequence!, musicSequenceUserCallback, Unmanaged.passUnretained(self).toOpaque()) if status == noErr { print("Callback registered successfully") } else { print("Callback registration failed: \(status)") } MusicPlayerStart(player!) } else { print("MIDI File Not Found") } } } The callback function was generated by Xcode and defined outside the ViewController. func musicSequenceUserCallback( clientData: UnsafeMutableRawPointer?, sequence: MusicSequence, track: MusicTrack, eventTime: MusicTimeStamp, eventData: UnsafePointer<MusicEventUserData>, startSliceBeat: MusicTimeStamp, endSliceBeat: MusicTimeStamp ) { print("User callback fired at eventTime: \(eventTime)") if let clientData = clientData { let controller = Unmanaged<ViewController>.fromOpaque(clientData).takeUnretainedValue() // Example usage to prove round-trip works (avoid strong side effects in callback) _ = controller.view // touch to silence unused warning if needed print("Callback has access to ViewController: \(controller)") } else { print("clientData was nil") } }

Hi I have a NSTextView set as the document of a NSScrollView scrollView.documentView = textView I want to programatically scroll to a specific offset in the scrollView. I use the following function and it jumps to the right location: scrollView.documentOffset = offset However I would like to animate the scrolling. Any suggestions? Also to mention, I have not flipped the coordinates of the NSTextView Thanks Reza

I have a borderless NSWindow with transparent background floating at Dock level and with collectionBehavior set to NSWindowCollectionBehaviorCanJoinAllSpaces. To render its background I was using an NSVisualEffectView, but, with the introduction of Liquid Glass, I decided to replace it with a NSGlassEffectView on Tahoe. On macOS 26.0 and 26.1 all works fine: my window's background is correctly rendered and updated. On macOS 26.2 this is not so: the background seems cached and doesn't update if I move my window or if I drag some other window underneath it. My window's movable property is set to NO (and I need this to be so): dragging is implemented by handling mouseDown, mouseDragged, and mouseUp events. Just to experiment, I tried setting movable and movableByWindowBackground both to YES. In this case, the NSGlassEffectView is correctly updated if I move the window itself, but doesn't change if I move other windows underneath it. Has anybody experienced a similar problem on maOS 26.2? If so, is there a way to solve it? Thanks, Marco

I need to create a Mac application using Objective-C. The application has to use PHPickerViewController to provide user a familiar interface to pick photos. Here is the Objective-C code that used to present the photo picker. //ViewController.h #import <Cocoa/Cocoa.h> #import <PhotosUI/PhotosUI.h> @interface ViewController : NSViewController<PHPickerViewControllerDelegate> @property (nonatomic, weak) IBOutlet NSImageView *myImageView; @end // ViewController.m @implementation ViewController PHPickerViewController* pickerViewController = nil; - (void)pickPhotos { PHPickerConfiguration *config = [[PHPickerConfiguration alloc] init]; config.selectionLimit = 0; // Allow multiple selections config.filter = [PHPickerFilter imagesFilter]; // Filter for images pickerViewController = [[PHPickerViewController alloc] initWithConfiguration:config]; pickerViewController.preferredContentSize = NSMakeSize(800, 600); pickerViewController.delegate = self; // Set the delegate to handle selection [self presentViewControllerAsModalWindow:pickerViewController]; - (IBAction)clicked:(id)sender { NSLog(@"Button Clicked"); [self pickPhotos]; } - (void)picker:(PHPickerViewController *)picker didFinishPicking:(NSArray<PHPickerResult *> *)results { if (pickerViewController) { [picker dismissViewController:pickerViewController]; } } @end Can you please guide me to show the photo picker to a bigger size?

I noticed that I cannot even tell that an NSBox is being used on macOS Tahoe when the system is in light mode. The 'box' background can't be seen so it makes it appear that the subviews in the box aren't positioned correctly (because they are inset from the subview outside the box). There is no visual indicator that that subviews inside this box are grouped together because well, you can't see the box at all. In Interface Builder the box looks fine at Design Time in "Light Mode". In Dark Mode the box looks fine at design time and at run time. Just figured I'd throw that out there.

So I noticed this: A sheet window is presented. The sheet window has some UI that makes it expandable say a little arrow expandable button. Click the little expandable button. Now the sheet window controller calls - (void)setFrame:display:animate: on its window to resize. The parent window flies across the screen to the lower left corner. I'm on Tahoe 26.1. Seems to be related to NSSheetMoveHelper. Not sure how long this bug has been around. Workaround is to call -setFrame:display:animate: and pass NO to the animate flag. Then the sheet window resizes (but not animated which doesn't look as good as the old behavior but better than suddenly disappearing). I think Apple may already knows about this bug b/c in an Apple app on Tahoe I see a sheet resizing being done with no animation...

Hi there! We have an application that exists for more than 10 years (Appkit, Obj-C), and since the very beginning we're using CMD+ESC as a keyboard shortcut for a very important function in our app. Until now, this worked great. Recently, when macOS 26.1 released our app started to not responding to CMD+ESC anymore for some of our customers - it seems like CMD+ESC never gets to our app at all. First, we though it's happening because Game Overlay is also using CMD+ESC by default, but when we turned that off, or switched that to something else in macOS's Keyboard preferences, the issue still persisted. The, we realized this has something to do with iCloud - so, if you turn off iCloud, do a log out and log in to your computer, and it's magically starts working again, as it always did. More strangely, this issue doesn't happen for everyone - for many of our customers, the issue seems to doesn't exist for some strange reason. Anyone have any idea what could be happening here?

Dear Forum, after decades, I'm back to MacOS dev just for the need of it. Besides Mac, I'm also toying around with vintage IBM mainframe systems and therefore I'm in need for a good terminal emulation. So far, I use x3270 on my Apple Silicon M1 MacBook Air - nice. However, I can't compile it on my collection of vintage Macs (iMac G3, Cube G4) so I pondered to create it on my own using Cocoa (starting with MacOS X 10.4 Tiger up to the current level (on Sequoia) so that rules out Carbon. tn3270 X from Brown University works nice on those vintage Macs but misses some features. Having browsed some info about the Cocoa Text system, I wonder if that would be the right place to start. At the end of the day, I need to be able to intercept all keystrokes, have more or less a fixed font 80x25 (136x25 etc..) col/row layout of protected and unprotected areas where text can be entered. Cusor should be visible and movable by using cursor control keys. I'd be happy for any suggestion on where to start here. Kind regards Michael

On Tahoe NSTextField (and NSTextFieldCell) appears to ignore backgroundColor, drawsBackground, isBezeled, bezelStyle and isBordered properties. Those worked on prior macOS, but not Tahoe. Is there a way to make those properties effective while targeting Tahoe? Note: a slight erratum: backgroundColor has an effect while the text field has first responder status, but the background area is an inset rectangle and I suspect that is a remnant feature and not by design.

My app (FindAnyFile) provides a Finder-like interface in which it also offers a QuickLook preview command, which invokes [[QLPreviewPanel sharedPreviewPanel] makeKeyAndOrderFront:nil]; Now, if it shows .abcdp files, it often, but not always, crashes. This has been happening for many macOS versions, at least since 10.15, up to 26.1. Also, it does not seem to matter which SDK/Xcode I build with, as I used several and all versions lead to the crash. The issue rather appears to be inside the QLplugin for the AB file (ABCardCollectionView etc.). I am able to trace this crash in Xcode. There are a LOT of errors and warnings coming up, and eventually the qlplugin throws an ObjC exception which in turn brings down my entire app (and here I thought that the XPC system was designed to expressly avoid such crashes). Possibly significant errors are: CNAccountCollectionUpdateWatcher 0x6000025cf800: Update event received, but store registration failed. This event will be handled, but the behavior is undefined. Error using remote object proxy when fetchAnonymousXPCEndpoint: Error Domain=NSCocoaErrorDomain Code=4097 "connection to service named com.apple.telephonyutilities.callservicesdaemon.callstatecontroller" UserInfo={NSDebugDescription=connection to service named com.apple.telephonyutilities.callservicesdaemon.callstatecontroller} connection to service named com.apple.coreduetd.people … CNPropertyNotFetchedException: A property was not requested when contact was fetched. I've attached the (mostly) complete console output from such a debug run. I have also an open bug report regarding this kind of crash (back then I was not able to reproduce it myself): FB15553847 Also, when I "Quick Look" the same file in Finder, I get a "Preview not permitted" for the same items that crash in my app. If I copy the same items to the Desktop, then Finder can QL them and my app doesn't crash when viewing the item on the Desktop. So, the crash only happens with the items inside ~/Library/Application Support/AddressBook/Sources/…/Metadata/. Now, here is the weirdest part: You might think: So, if the Finder shows "Preview not permitted", then my app trying to view those items is the result of that condition (even if that's not supposed to crash). However: I have a clean 26.1 install (in an Apple ARM VM) where Finder also says "Preview not permitted" for these items in the user's Library/AB/Metadata folder, but my app can QL those items without crashing! Also, I have one user who uses 26.1 and gets the crash with files in the same location. So, the "Preview not permitted" is probably not the cause of this crash, though it's suspicious that a user gets this at all - why can't a user QL the abcdp files in the Metadata folder but when copied to the Desktop, QL works? You'd think that Finder has the necessary entitlements to access the AB, or doesn't it? Of course, my app has permission enabled under Privacy & Security / Contacts (if it's disabled, then the app can't show anything but will also not crash). And it has the "Address Book" entitlement. Would be nice if this could be looked into and eventually be fixed. Alternatively, I'd welcome any suggestions on how to prevent my app from crashing if the qlplugin throws. But if you look at the stack trace you'll see that there's no method of my own app involved where I could insert an exception catcher. I added code to my previewItemURL delegate method to make sure the NSURL item is readable, and it is, even Of course, apart from the issue with .abcdp files, the QL operation in my app works flawlessly, i.e. I have never received any other crash reports relating to any other QL plugins. QuickLook for AddressBook crash messages

I'm reading a bit outdated book about Cocoa/Objective-C applications development and I'm trying to code some examples. And so I ended up with an almost empty NSDocument-based app with runtime errors like that: Internal inconsistency in menus - menu <NSMenu: 0xbc726d040> Title: Window Supermenu: 0xbc726d080 (Main Menu), autoenable: YES Previous menu: 0x0 (None) Next menu: 0x0 (None) Items: ( "<NSMenuItem: 0xbc6fcd9a0 Minimize, ke='Command-M'>", "<NSMenuItem: 0xbc6fcda40 Zoom, ke mask=''>", "<NSMenuItem: 0xbc6fcdae0, separator, ke mask=''>", "<NSMenuItem: 0xbc6fcd900 Bring All to Front, ke mask=''>" ) believes it has <NSMenu: 0xbc726d080> Title: Main Menu Supermenu: 0x0 (None), autoenable: YES Previous menu: 0x0 (None) Next menu: 0x0 (None) Items: ( ) as a supermenu, but the supermenu does not seem to have any item with that submenu It looks like as if the menu tries to include itself as a submenu. Am I right? I have no ideas what led to this. If I'm not mistaken this has started since macOS Tahoe. The code that is not a boilerplate one I have: // Document.m #import "Document.h" @implementation Document @synthesize text; - (NSString *)windowNibName { return @"SampleDocument"; } - (void)windowControllerDidLoadNib:(NSWindowController *)aController { [super windowControllerDidLoadNib:aController]; if (self.text == nil) { self.text = @""; } self.textField.stringValue = self.text; } - (NSData *)dataOfType:(NSString *)typeName error:(NSError **)outError { self.text = self.textField.stringValue; return [self.text dataUsingEncoding:NSUTF8StringEncoding]; } - (BOOL)readFromData:(NSData *)data ofType:(NSString *)typeName error:(NSError **)outError { if ([data length] > 0) { NSString * string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]; self.text = string; } else { self.text = @""; } return YES; } + (BOOL)autosavesInPlace { return YES; } @end There are two xib's: MainMenu.xib and Document.xib but I won't include them here. Please advise how to fix this menu issue.

Appkit starting logging these warnings in macOS 26.1 about my app's MainMenu. **Internal inconsistency in menus - menu <NSMenu: 0xb91b2ff80> Title: AppName Supermenu: 0xb91a50b40 (Main Menu), autoenable: YES Previous menu: 0x0 (None) Next menu: 0x0 (None) Items: () believes it has [<NSMenuSubclassHereThisIsTheMenuBarMenuForMyApp:] 0xb91a50b40> Title: Main Menu Supermenu: 0x0 (None), autoenable: YES Previous menu: 0x0 (None) Next menu: 0x0 (None) Items: ( ) as a supermenu, but the supermenu does not seem to have any item with that submenu ** I don't what that means. The supermenu is the menu that represents the menu used for my app's menu bar (as described by NSMenuSubclassHereThisIsTheMenuBarMenuForMyApp Everything seems to work fine but log looks scary. Please don't throw!

I want to check whether a sandboxed application already has access permission to a specific URL. Based on my investigation, the following FileManager method seems to be able to determine it: FileManager.default.isReadableFile(atPath: fileURL.path) However, the method name and description don't explicitly mention this use case, so I'm not confident there aren't any oversights. Also, since this method takes a String path rather than a URL, I'd like to know if there's a more modern API available. I want to use this information to decide whether to prompt the user about the Sandbox restriction in my AppKit-based app.

the app crashes about 10 seconds after it goes into the background libsystem_kernel.dylib semaphore_wait_trap 100% 45 dyld start + 7116 [0x1825fa000] 100% 44 xxxx main + 76 (main.m:38) [0x104c14000] 100% 43 UIKitCore UIApplicationMain + 336 [0x18ae57000] 100% 42 UIKitCore -[UIApplication _run] + 792 [0x18ae57000] 100% 41 GraphicsServices GSEventRunModal + 120 [0x224975000] 100% 40 CoreFoundation _CFRunLoopRunSpecificWithOptions + 532 [0x185569000] 100% 39 CoreFoundation __CFRunLoopRun + 820 [0x185569000] 100% 38 CoreFoundation __CFRunLoopDoSources0 + 232 [0x185569000] 100% 37 CoreFoundation __CFRunLoopDoSource0 + 172 [0x185569000] 100% 36 CoreFoundation __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28 [0x185569000] 100% 35 BoardServices BSServiceMainRunLoopSourceHandler + 224 [0x19c8b0000] 100% 34 BoardServices __BSSERVICEMAINRUNLOOPQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 52 [0x19c8b0000] 100% 33 libdispatch.dylib _dispatch_block_invoke_direct + 284 [0x1bcf40000] 100% 32 libdispatch.dylib _dispatch_client_callout + 16 [0x1bcf40000] 100% 31 FrontBoardServices -[FBSWorkspace _calloutQueue_executeCalloutFromSource:withBlock:] + 168 [0x1a4d45000] 100% 30 FrontBoardServices __94-[FBSWorkspaceScenesClient _queue_updateScene:withSettings:diff:transitionContext:completion:]_block_invoke_2 + 96 [0x1a4d45000] 100% 29 FrontBoardServices __94-[FBSWorkspaceScenesClient _queue_updateScene:withSettings:diff:transitionContext:completion:]_block_invoke_2.cold.1 + 352 [0x1a4d45000] 100% 28 FrontBoardServices -[FBSScene updater:didUpdateSettings:withDiff:transitionContext:completion:] + 708 [0x1a4d45000] 100% 27 FrontBoardServices -[FBSScene _callOutQueue_maybeCoalesceClientSettingsUpdates:] + 128 [0x1a4d45000] 100% 26 FrontBoardServices __76-[FBSScene updater:didUpdateSettings:withDiff:transitionContext:completion:]_block_invoke.129 + 380 [0x1a4d45000] 100% 25 UIKitCore -[UIApplicationSceneClientAgent scene:handleEvent:withCompletion:] + 336 [0x18ae57000] 100% 24 UIKitCore -[UIScene scene:didUpdateWithDiff:transitionContext:completion:] + 244 [0x18ae57000] 100% 23 UIKitCore -[UIScene _emitSceneSettingsUpdateResponseForCompletion:afterSceneUpdateWork:] + 208 [0x18ae57000] 100% 22 UIKitCore __64-[UIScene scene:didUpdateWithDiff:transitionContext:completion:]_block_invoke.218 + 616 [0x18ae57000] 100% 21 UIKitCore -[_UIWindowSceneFBSSceneTransitionContextDrivenLifecycleSettingsDiffAction _performActionsForUIScene:withUpdatedFBSScene:settingsDiff:fromSettings:transitionContext:lifecycleActionType:] + 316 [0x18ae57000] 100% 20 UIKitCore _UISceneSettingsDiffActionPerformChangesWithTransitionContextAndCompletion + 224 [0x18ae57000] 100% 19 UIKitCore +[BSAnimationSettings(UIKit) tryAnimatingWithSettings:fromCurrentState:actions:completion:] + 736 [0x18ae57000] 100% 18 UIKitCore __186-[_UIWindowSceneFBSSceneTransitionContextDrivenLifecycleSettingsDiffAction _performActionsForUIScene:withUpdatedFBSScene:settingsDiff:fromSettings:transitionContext:lifecycleActionType:]_block_invoke + 148 [0x18ae57000] 100% 17 UIKitCore -[_UISceneLifecycleMultiplexer uiScene:transitionedFromState:withTransitionContext:] + 244 [0x18ae57000] 100% 16 UIKitCore -[_UISceneLifecycleMultiplexer _evalTransitionToSettings:fromSettings:forceExit:withTransitionStore:] + 608 [0x18ae57000] 100% 15 UIKitCore -[_UISceneLifecycleMultiplexer _performBlock:withApplicationOfDeactivationReasons:fromReasons:] + 212 [0x18ae57000] 100% 14 UIKitCore __101-[_UISceneLifecycleMultiplexer _evalTransitionToSettings:fromSettings:forceExit:withTransitionStore:]_block_invoke + 252 [0x18ae57000] 100% 13 UIKitCore _UIScenePerformActionsWithLifecycleActionMask + 112 [0x18ae57000] 100% 12 UIKitCore __101-[_UISceneLifecycleMultiplexer _evalTransitionToSettings:fromSettings:forceExit:withTransitionStore:]_block_invoke_2 + 512 [0x18ae57000] 100% 11 UIKitCore -[UIApplication _applicationDidEnterBackground] + 136 [0x18ae57000] 100% 10 UIKitCore +[UIViewController _performWithoutDeferringTransitionsAllowingAnimation:actions:] + 140 [0x18ae57000] 100% 9 UIKitCore __47-[UIApplication _applicationDidEnterBackground]_block_invoke + 256 [0x18ae57000] 100% 8 Foundation -[NSNotificationCenter postNotificationName:object:userInfo:] + 92 [0x182c3d000] 100% 7 CoreFoundation _CFXNotificationPost + 736 [0x185569000] 100% 6 CoreFoundation _CFXRegistrationPost + 436 [0x185569000] 100% 5 CoreFoundation ___CFXRegistrationPost_block_invoke + 92 [0x185569000] 100% 4 CoreFoundation __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 148 [0x185569000] 100% 3 CoreBluetooth -[CBXpcConnection _sendBarrier] + 188 [0x1c2254000] 100% 2 libdispatch.dylib _dispatch_semaphore_wait_slow + 132 [0x1bcf40000] 100% 1 libdispatch.dylib _dispatch_sema4_wait + 28 [0x1bcf40000] 100% 0 libsystem_kernel.dylib semaphore_wait_trap + 8 [0x22d5b6000]

In my AppKit app I have a an outline view where each cell has a title (NSTextField), image view (NSImageView), and 4 NSButtons that are essentially static badges (their .bezelStyle is set to .badge). I’ve seeing very low performance when doing quick reloads in successions, for example when filtering data. My app is built on macOS Tahoe. Profiling the app in instruments I can see that each initialization takes more than 70ms. Does this make sense? Thanks!

Hi all, when I launch my macOS app from Xcode 16 on ARM64, appKit logs me this error on the debug console: It's not legal to call -layoutSubtreeIfNeeded on a view which is already being laid out. If you are implementing the view's -layout method, you can call -[super layout] instead. Break on _NSDetectedLayoutRecursion(void) to debug. This will be logged only once. This may break in the future. _NSDetectedLayoutRecursion doesn't help a lot, giving me these assembly codes from a call to a subclassed window method that looks like this: -(void) setFrame:(NSRect)frameRect display:(BOOL)flag { if (!_frameLocked) [super setFrame:frameRect display:flag]; } I have no direct call to -layoutSubtreeIfNeeded from a -layout implementation in my codes. I have a few calls to this method from update methods, however even if I comment all of them, the error is still logged... Finally, apart from that log, I cannot observe any layout error when running the program. So I wonder if this error can be safely ignored? Thanks!

I have Mac apps that embed “Helper Apps” inside their main bundle. The helper apps do work on behalf of the main application. The helper app doesn’t show a dock icon, it does show minimal UI like an open panel in certain situations (part of NSService implementation). And it does make use of the NSApplication lifecycle and auto quits after it completes all work. Currently the helper app is inside the main app bundle at: /Contents/Applications/HelperApp.app Prior to Tahoe these were never displayed to user in LaunchPad but now the Spotlight based AppLauncher displays them. What’s the recommended way to get these out of the Spotlight App list on macOS Tahoe? Thanks in advance.

Is there a way that an AppKit application can determine which Liquid Glass option has been selected in System Settings (Clear or Tinted)?

My app has the following UI layout: NSSplitViewController as the windows contentViewController NSPageController in the content (right) split item NSTabViewController as the root items of the NSPageController NSViewController with a collection view in the first tab of that NSTabViewController The collection view is using a NSCollectionViewCompositionalLayout in which the sections are set up to have a header using NSCollectionLayoutBoundarySupplementaryItem with pinToVisibleBounds=true and alignment=top With macOS 26, the pinned supplementary item automatically gets a blurred/semi-transparent background that seamlessly integrates with the toolbar. When the window's title bar has a NSTitlebarAccessoryViewController added, the said semi-transparent background gets a bottom hard edge and a hairline to provide more visual separation from the main content. During runtime, my NSPageController transitions from the NSTabViewController to another view controller. When transitioning back, the semi-transparent blur bleeds into the entire section. This happens no matter if there's a NSTitlebarAccessoryViewController added or not. It doesn't happen 100% of the cases, it seems to depend on section size, header visibility and/or scroll position. But it happens more often than not. Most of the time, a second or so after the back transition - shortly after pageControllerDidEndLiveTransition: of the NSPageControllerDelegate is called - the view updates and the supplementary views are back to normal. Sometimes, the issue also appears not when transitioning using NSPageController, but simply by scrolling through the collection view. Anyone has an idea what is happening here? Below are two screenshots of both the "ok" and "not ok" state I'm on macOS 26.0.1 and I'm using XCode 26.0.1