What is the point of "concentricity" on a Mac?

[2638se]

Apple said they want concentricity as the justification for all the corner madness but I just can't get it, since all the texts/pictures/videos are squared (Also the display itself??? all corners for external displays, bottom corners for MacBooks). Why do they choose "concentricity" with Tool Bar/traffic lights at the top while cutting through content at bottom for no reason?? When they explicitly state they want to emphasize the content?

1. Safari 2. QuickLook 3. Pages
Somebody shot/drew/wrote that and I want to see all of It!
The Snow Leopard approach is perfect imo, It rounds the top but keeps the bottom squared.

Before Alan Dye shows up and says nobody cares about corners:
1. Then why change them??
2. A lot of people do.
3. If you want to be a free shill for this trillion dollar faceless corporation, why don't you argue with the messiah for that corporation first?
“When you’re a carpenter making a beautiful chest of drawers, you’re not going to use a piece of plywood on the back, even though it faces the wall and nobody will ever see it. You’ll know it’s there, so you’re going to use a beautiful piece of wood on the back. For you to sleep well at night, the aesthetic, the quality, has to be carried all the way through.”
― Steve Jobs

 

[!!!]

My conspiratorial take is that they're increasing padding and making things more rounded in order to waste space, so your screen "feels" smaller: less content is shown. And hey look, Apple sells larger screens (for more $$$).

The more likely explanation is that the guy in charge (Alan Dye, who is now a stalker) told the team that rounded corners were good, and more rounded corners is more good. So now we have rounded corners for our rounded corners (see the finder sidebar).

Somebody shot/drew/wrote that and I want to see all of It!

Apple is speaking in doublespeak when they claim that LG "gives way to the content", in reality it places itself in front of the content, it's narcissism by Apple as they believe their UI is more beautiful than anything you can possibly be trying to look at.

 

[svenmany]

Apple said they want concentricity as the justification for all the corner madness but I just can't get it, since all the texts/pictures/videos are squared (Also the display itself??? all corners for external displays, bottom corners for MacBooks). Why do they choose "concentricity" with Tool Bar/traffic lights at the top while cutting through content at bottom for no reason?? When they explicitly state they want to emphasize the content?

View attachment 2623101
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1. Safari 2. QuickLook 3. Pages
Somebody shot/drew/wrote that and I want to see all of It!
The Snow Leopard approach is perfect imo, It rounds the top but keeps the bottom squared.

Before Alan Dye shows up and says nobody cares about corners:
1. Then why change them??
2. A lot of people do.
3. If you want to be a free shill for this trillion dollar faceless corporation, why don't you argue with the messiah for that corporation first?
“When you’re a carpenter making a beautiful chest of drawers, you’re not going to use a piece of plywood on the back, even though it faces the wall and nobody will ever see it. You’ll know it’s there, so you’re going to use a beautiful piece of wood on the back. For you to sleep well at night, the aesthetic, the quality, has to be carried all the way through.”
― Steve Jobs

I would love to see some interview with one of the designers who asserted that concentricity was important and see how he responds to the impossibility of achieving it.

Do you have a link where they talk about this concentricity? (never mind - I found some discussion)

 

[svenmany]

I'm grateful for this thread since it motivated me to search for discussions about concentricity on Tahoe. Till just now I hadn't realized that it was actually Apple's intention that windows not have consistent corner radiuses. Their intention is that you (as a developer) try to make things concentric with what's at the top of the window. So windows with the new large-icon toolbars are trying to have the window's corners be concentric with that. Windows without those toolbars I guess are choosing something at random since there really is nothing as obvious to be concentric with.

It seems very strange. I think there's an Apple video that talks about this. I'll have to watch it.

 

[svenmany]

Well, I watched the video at https://developer.apple.com/videos/play/wwdc2025/323/ and did some research about the API with regard to concentricity. Technically, the support for concentricity involves inner things trying to match the roundedness of their containers - not the other way around. That would imply the new toolbars are rounded as they are because the containing windows are.

I don't see any references (except in casual discussions by third-parties) that concentricity motivated the choice of corner curvature of windows. Does anyone have any link where Apple actually asserts this?

I had a nice conversation with Claude about this. I managed to convince it that it was wrong when it said that concentricity drove the window corner choices. It was basing that opinion from Apple's WWDC 2025 session videos.

After I saw that Claude was wrong (which I often do), I wrote:

But, if a window has a toolbar and is set to have corners concentric with its container, then a window having smaller corner radius would result in toolbars having smaller corner radiuses. So, concentricity doesn't seem to be the driving motivation for the choice of the window's corner radius.

to which Clause responded in a way that helps to pinpoint the flaw in Apple's design:

That's a sharp observation. You're essentially pointing out a logical inversion in Apple's stated rationale: if concentricity is the governing principle, then the window corners should be derived from whatever is inside them, but a window's corner radius is actually a fixed property of the window style — it doesn't respond to what's nested inside it. The toolbar elements are made concentric with the window, not the other way around.

In other words, Apple's explanation as stated in the WWDC session has the causality backwards. The window corner radius is chosen first (and made larger), and then toolbar elements are told to be concentric with that. Concentricity is a consequence of that design, not the motivation for the size choice. If concentricity were truly the driver, you could achieve it equally well with a smaller window corner radius — you'd just get smaller toolbar corners, which would also be concentric.

So the actual motivation for the larger radius must be something else — aesthetic preference, alignment with hardware display corners, the "softer feel" Apple mentions — and concentricity is better understood as a design discipline applied on top of that choice, ensuring internal elements harmonize with whatever the window radius turns out to be.

It's worth noting that Apple's design sessions do frame concentricity as creating "a unified rhythm between hardware and software" Apple Developer — which hints that the real anchor point for the radius choice may actually be the physical device bezel, not the toolbar elements. That would make more logical sense: hardware corners → window corners → toolbar corners, as a chain of concentricity, rather than toolbar corners driving window corners.

On macOS there are no fixed hardware corners. So, I would assert that the extra roundedness of the windows on macOS (not iOS) is purely an aesthetic choice by the Apple designers and not motivated by concentricity.

 

[FreakinEurekan]

On macOS there are no fixed hardware corners.

Well - SOMETIMES there is.

On my M1 Max 16" the top corners of the display are rounded; the bottom corners are square.

Curiously, most Apple apps use "roughly" the same rounding as the hardware top-corner for window corners. Safari, Messages, Mail, Photos, Maps - all match that.

Third-party apps, though, it varies... Quicken, Google Earth, and 1Password all use a smaller radius curve. Photoshop uses even smaller than those.

Here is Photoshop, with Quicken on top of that, and Safari on top of that.

And a literal photo, so you can see the hardware corner:

 

[M4th]

Yet another idea about "concentricity"...

 

[turbineseaplane]

I really don’t understand it either.

All I can think of is that they’re just trying to be different.

It’s quite an uphill battle on design when you’ve decided to encapsulate and really round everything. You’re fighting the fact that, to your point, you’re starting from rectangles everywhere.

 

[hieubui]

what if they're not wasting space, but making room for your finger?

 

[turbineseaplane]

what if they're not wasting space, but making room for your finger?

Then they should get on with it and release macOS for iPads as well as do Touchscreen Mac options.

There's no need to be screwing up macOS for that possible usage until hardware exists that benefits from it.

 

[svenmany]

On macOS, the desire for concentricity does not consider the screen or hardware at all. Concentricity drives the window rounding because of a desire to establish concentricity with the toolbar controls. So, if they did use smaller toolbar buttons, then the window rounding would be less.

Circles are concentric when the centers are at the same point. There are no circles involved and the corners are often offset horizontally or vertically within their containing frame. I tried to explain the API's notion of concentric by writing it here, but it got too hard and I realized no one would care. Suffice it to say that if you move the inner frame away from its container's edge, then its curvature has to be less (smaller radius of curvature) to stay concentric. Since on macOS a window can be easily moved closer to or away from the screen's corner, concentricity considerations could never take into account the hardware's or screen's corner curvature.

People have often said that this whole window corner thing is caused by Apple's desire to support touch screens. I finally understand the point. If Apple is completely stuck on concentricity, then they have to keep the window rounding large so that the toolbar buttons stay large. They need the toolbar buttons to stay large to support being pressed reliably by a fat finger.

Purely a subjective opinion - I think that concentricity can work on iOS as a motivating design driver, but it is completely out of place on macOS. The two key differences on macOS are:

1 - Windows can move around within the screen's display area. Therefore, windows themselves will always fail to be concentric with their container (the screen). The fundamental design principle of concentricity fails at the most obvious visual artifact - the window itself.

2 - Users are often looking at multiple windows at the same time. The inconsistency between the windows will always be a problem.

I watched a bunch of Apple videos on this. My sense was that their whole thought process was driven by examples they showed from iPhone screens. Of course, on an iPhone the windows are always the full screen and concentricity with the screen itself is achievable.

 

[droplink]

what if they're not wasting space, but making room for your finger?

Then they can do that on that interface.
No one has a problem with larger buttons on iPhones / iPads where you need extra space and where clicking the traffic light buttons could be a problem.
People complain about the computer screen real estate being waster.

 

[tomtad]

I watched a bunch of Apple videos on this. My sense was that their whole thought process was driven by examples they showed from iPhone screens. Of course, on an iPhone the windows are always the full screen and concentricity with the screen itself is achievable.

It's exactly this.

Everything to do with Liquid Glass came from the iPhone and iPad, it was envisioned as a touch interface, elements are designed to be round (to match your finger) and also match the concentricity of the hardware, a nice integration of hardware and software which Apple only can do.

This doesn't make much sense however when it's expanded to the Mac. I see why they ended up with such rounded corners but really it doesn't seem to work on Mac.

 

[Howard2k]

Apple likely knows that in the real world the overwhelming majority of people simply don't care about a square screen corner and a rounded window corner, but they can see the theme of rounded corners on a crowded desktop with plenty of non-fullscreen windows.

 

[chrono1081]

Well - SOMETIMES there is.

On my M1 Max 16" the top corners of the display are rounded; the bottom corners are square.

Curiously, most Apple apps use "roughly" the same rounding as the hardware top-corner for window corners. Safari, Messages, Mail, Photos, Maps - all match that.

Third-party apps, though, it varies... Quicken, Google Earth, and 1Password all use a smaller radius curve. Photoshop uses even smaller than those.

Here is Photoshop, with Quicken on top of that, and Safari on top of that.View attachment 2623246
And a literal photo, so you can see the hardware corner:
View attachment 2623247

A big problem with this is Apples "concentricity" option is pure ass. I've literally never gotten it to work once, neither has anyone else on my team. There seems to be just some random rules about it that may/may not work (and yes I watched the WWDC video).

 

[svenmany]

A big problem with this is Apples "concentricity" option is pure ass. I've literally never gotten it to work once, neither has anyone else on my team. There seems to be just some random rules about it that may/may not work (and yes I watched the WWDC video).

Interesting. Finder's left sidebar's frame is concentric with the window. They might have achieved that by manually specifying the sidebar's curvature, rather than specifying that it be concentric. If concentricity in the API really doesn't work, as you're suggesting, then Apple could be doing that.

Notice that when you add toolbar buttons to the toolbar, you can use spacers to control whether buttons get grouped with other ones or not. If you do that, the button's curvature will be based on the that choice. Again, they could be doing that manually or using concentricity in the API to take care of it automatically.

Can you share a code snippet that you think should work but doesn't?

 

[ProbablyDylan]

Apple is speaking in doublespeak when they claim that LG "gives way to the content", in reality it places itself in front of the content, it's narcissism by Apple as they believe their UI is more beautiful than anything you can possibly be trying to look at.

100%. It literally asserts itself above the content, distorting it beneath it.

 

[svenmany]

100%. It literally asserts itself above the content, distorting it beneath it.

I'd pay money to attend an interview with one of those designers where they are challenged to defend their position on this. I'm trying to imagine what they think the value is in showing an extra portion of content that's obscured by controls hovering above it.