NSToolbar items don’t react to Dark Mode changes in apps compiled with macOS 15 SDK: My app was installed as a notarized app on a Tahoe VM with the same build as distributed in the App Store, based on macOS 15 SDK. When toggling Dark Mode, toolbar items are not updated, but only after opening a new window / tab or e.g. customizing the toolbar. The app is using default methods for the toolbar, defined in its corresponding XIB file, and working in previous macOS versions. This issue could be confirmed with various apps built with an SDK prior to macOS 26 "Tahoe", e.g. Apple's Clipboard Viewer. Reported via Feedback Assistent (FB19107572).

Just posted this feedback regarding macOS 26 "Tahoe" (FB19853155) - please support with additional submissions if you share my view. I will miss the beautiful and individual designed icons of the past! "macOS 26 is enforcing squicles for app icons, falling back to a grey background for 3rd party apps without a compliant AppIcon asset. As a result many original app icons are reduced in size and hard to distinguish because they share the same background color. Although I respect Apple's strive for an iOS-like UI on Macs, a smooth transition path would be more user- and developer-friendly ... e.g. with some info.plist property to opt-out icon migration, potentially ignored by a future macOS version. The current solution causes a bad usability, and makes the system look inconsistent as many - especially free - software will not be updated with new icon designs. Please reconsider this bad design decision!"

After installing my notarized 3rd party app in a Tahoe VM, its embedded Automator actions can not be configured in Automator while defining a workflow: After adding the actions (enabling 3rd party extensions), their views / UI elements do not respond to any mouse event. When enabling „show this action when running“, the options can be changed during execution of the workflow. Needless to say: Adjusting these action settings in Automator was working for years, macOS 12 - 15 and before. Reported via Feedback Assistent (FB19015185). Can anybody confirm this issue with Automator actions?

When disabling the opacity slider of color panels, my app crashes with unsatisfiable layout constraints. Feel free reproduce with a minimal test project: A macOS app based on the Xcode 26.0 template with only one line added to the ViewController's viewDidLoad() function: NSColorPanel.shared.showsAlpha = false The issue doesn't occur if this property is set to "true" or not set at all. I just filed a corresponding bug report (FB20269686), although I don't expect any feedback from Apple ... as numerous issues I reported were never updated or commented at all (after migrating from RADARs).

When I compiled my legacy project with Tahoe's macOS 26 SDK, NSRulerViews are showing a very different design: Under prior macOS versions the horizontal and verrical ruler's background were blurring the content view, which was extending under the rulers, showing through their transparency. With Tahoe the horizontal ruler is always reflecting the scrollview's background color, showing the blurred content view beneath. And the vertical ruler is always completely transparent (without any blurring), showing the content together with the ruler's markers and ticks. It's difficult to describe, I'll try to replicate this behavior with a minimal test project, and probably file a bug report / enhancement request. But before I take next steps, can anyone confirm this observation? Maybe it is an intentional design decision by Apple?