NSRulerView's background color and transparency (macOS 26)

Question

Created Sep ’25

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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?

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Answer 1

MyMattes OP

Sep ’25

Okay, let's try to sort this out a bit - I was confused facing a couple of different issues:

NSRulerViews are showing inconsistent Backgrounds: With macOS 26 NSRulerViews are showing a very different layout, not only in contrast to prior macOS versions, but also inconsistent between horizontal and vertical rulers. I filed a corresponding bug report (FB20342342)
- The horizontal ruler view is showing with a solid color. I assume the color is selected based on the first line of the inner view, because with a transparent content view the scrollview's background color is used, otherwise the content view's background color.
- The vertical ruler view is using a much lighter or transparent version of the content view's background, what I would consider the intended (and expected) behavior.
NSRulerView is obscuring content in full screen: Custom apps are facing an incorrect behavior of NSRulerViews when running in full screen: The height of the horizontal ruler is increased, obscuring the top of the clipview. I observed this issue with one of my apps, but was able to replicate it with a minimal sample app, using a scrollable text view with rulers, refer to the attached screenshots. Again, I files a bug report (FB20342122)

Window mode: RulerTest - Window.png

Full Screen: RulerTest - FullScreen.png

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Answer 2

MyMattes OP

2w

I'm still unsure if the different color of horizontal ruler views is a bug or the intended design under macOS 26.

Therefore, I filed a DTS incident (Apple Developer Technical Support, TSI), asking for a way to customize an NSRulerView's background color...

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Answer 3

DTS Engineer OP

Apple

2w

Thank you for your post. We have received the DTS incident report and the two bug reports. Your comprehensive information is greatly appreciated.

At this time, we recommend utilizing the forums to benefit all developers who may encounter similar issues. The engineering team is currently reviewing the focus samples and information you have provided. Lets give them sometime to figure it out.

In the meantime. You can see the status of your feedback in Feedback Assistant. There, you can track if the report is still being investigated, has a potential identifiable fix, or has been resolved in another way. The status appears beside the label "Resolution." We're unable to share any updates on specific reports on the forums.

For more details on when you'll see updates to your report, please see What to expect after submission.

Albert Pascual   Worldwide Developer Relations.

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