[dylan-m]

One of my favourite unreported MacOS issues comes from how, at some point, they changed the appearance of the window close button to be a particular shade of red with a tiny little X in the center. And if you happen to be using a particular kind of screen and possibly wearing glasses, that little X kind of wanders around in the button, appearing just slightly off center in a maddening way. Made only more maddening by the glasses component: https://www.robbert.org/2014/10/the-off-center-close-button/.

That post points out it’s probably just subpixel stuff causing the issue, but I think my thick, cheap glasses at the time were adding a layer of chromatic aberration to something that was already visually confusing.

I assume it’s kind of gone away at this point with all the high DPI screens these days. But I remember thinking at the time, if there was a public bug tracker, that issue would be a fun one.

[mrob]

>More expensive lenses have a coating to compensate for this chromatic aberration.

You can't compensate for chromatic aberration with a coating. You need a compound lens made from multiple elements each with a different dispersion, e.g.:

https://en.wikipedia.org/wiki/Achromatic_lens

More expensive glasses lenses usually have worse chromatic aberration than cheap ones. The cheapest material for glasses lenses (PADC, often called by the brand name CR-39) has one of the best Abbe numbers (measure of dispersion).

https://en.wikipedia.org/wiki/CR-39

https://en.wikipedia.org/wiki/Abbe_number

[w4rh4wk5]

I can confirm this. I had annoyingly bad chromatic aberration with my previous glasses. I specifically asked for CR-39 lenses for my next set of glasses and now it's barely noticeable at all.

I would recommend this to any programmer who uses high-contrast syntax highlighting. To me, it felt fatiguing every time I noticed differently colored words scrolling slight further than other words on a terminal screen on the same line.

[cubefox]

I thought I got used to the color fringes in my glasses, but the real problem is that they actually reduce image clarity away from the center of the lenses. If you look e.g. at white text on a dark background from an angle, the chromatic aberration blurs (the color components of) the letters together. You can't really see clearly by moving the eyes to the edge of the FoV of your glasses; you have to turn your head instead.

This is directly contradicting the main purpose of glasses: to see clearly. So it's actually somewhat less safe to e.g. drive with glasses that have major chromatic aberration. No idea why optometrists brush it off as a minor glitch.

[germinalphrase]

I can’t speak to glasses, but limiting chromatic aberration in the binocular world does seem to involve coatings (at least as Swarovski, Leica, Zeiss present it).

[kortilla]

Can you link to something to buy?

[azlev]

TIL. Thank you.

[jahnu]

Another irritating thing that is captured in that image is the single pixel gap between the top of the application window and the menu bar. If the desktop background is bright it is very distracting. Not a mistake like the off centre X but drives me mad, nevertheless.

[jeffhuys]

I knew from the very start of using macOS that it was designed around apps NOT being full-screen. Yeah, they are catering to the full-screen-apps people a little more nowadays, but embracing floating windows everywhere, and making good use of the distinction betweend CMD+Tab and CMD+~ makes it so much more powerful than just tabbing through full-screen apps, or three-finger-swiping. It also makes macOS way more beautiful to look at in my opinion.

[sph]

That gap provides contrast and separation between two similarly-coloured-but-not-quite grey objects. It would look worse without it, though I agree it is silly.

This is the same reason why window gaps are so popular in all tiling window managers. It just looks better.

[trilbyglens]

This is not a software bug, but rather an optical phenomenon called "chromatic aberration". What's happening is that your glasses are bending light at different angles depending on the wavelength, to the red and blue and green are landing at slightly different places on your retina.

It's a hard problem to solve optically and requires specially shaped lens. It's a common issue in telescopes, with higher end expensive scopes having these specially shaped lenses to reduce this effect.

[voctor]

From the post:

> In conclusion, the off-center “x” is real and probably an artifact of the display or how it is rendered. It is unlikely that it is the result of chromatic aberration.

[almostnormal]

Chromatic aberration is mostly relevant further away from the center of vision. If there is an icon (or text) visually inspected carefully it is at the center where chromatic aberration matters least.

The icon is mis-aligned, or its the different color subpixels of the screen that are not produced at the same place. Tradidionally, red is to the left.

[dustincoates]

Is this why, when I'm reading text on a dark background, red will appear on a different plane than white? I was just wondering the reason last night.

[meta-level]

from the comment:

> That post points out it’s probably just subpixel stuff causing the issue, but I think my thick, cheap glasses at the time were adding a layer of chromatic aberration to something that was already visually confusing.

[johnwalkr]

When I got an ultra wide monitor I also noticed this for the first time on the macOS circular red X button, when wearing glasses. I guess a wide monitor has you looking at things off-axis more. It is really remarkable how much you can make the X dance around the red circle by moving your head. There's something about the colours and simplicity of that particular icon that really cause the effect. The effect is almost non-existent if you're looking at a more complex image, so I guess it's also remarkable how much your brain compensates for chromatic aberration in most contexts.

[hedora]

My glasses cause a bit of chromatic aberration, but not enough that I'd expect to see this sort of effect except at the edges of their field of view.

Now that you point it out, the X is way off center on my up-to-date M2, so I took a screenshot with default display settings and zoomed in to look at the pixel work.

The X is rendered asymmetrically. It appears to be about 0.1 pixels too far to the left and down, since the antialiasing has shaded pixels "outside the X" but only on those sides. The antialiased render of the red circle is symmetric. This matches what I see without zooming in and rules out my glasses.

I wonder if someone fixed the bug for low-dpi displays where subpixel rendering mattered a lot, but did so in a way that hard-coded whatever Apple shipped 10 years ago. Maintaining tall piles of hacks is hard.

Alternatively, maybe their font renderer is getting wobbly in its old age. The window manager is my #1 complaint about this laptop, but crappy font rendering vs. well-configured Linux is also on my list.

[trustno2]

I mean horizontal and vertical centering is the hardest thing in computer science

[amelius]

Honestly what annoys me most is that it looks like a sideways traffic light.