As I was working on some GUI I was quite obsessed with rendering rounded rects. And I remembered something funny:

When I was a kid I was programming a lot on my Atari ST (in 68000 with Devpac). So when my dad brought a Macintosh at home I couldn’t help myself trying to access the 68040 as much as I could.

And I had to reverse engineer almost everything I was capable of (and everything that was under my hands in the end) to try to understand how the system (System 7) was working (at that time internet didn’t exist and getting information was hard and costly).

And it happened that I found out some peculiar code that was erasing (setting to black) some pixels in the borders of the frame buffer.

I first wondered what was the goal of having these few pixels always set to black.

But it was made to provide users with rounded corners!!!

Sounds like I am not the only one to be obsessed with rounded rects!