As a programmer writing OS-level utility software for Macs back in the day, I stumbled across one of the MS-preservation hacks in Mac OS. I wrote about it here

As a programmer writing OS-level utility software for Macs back in the day, I stumbled across one of the MS-preservation hacks in Mac OS. I wrote about it here on Hacker News twelve years ago: https://news.ycombinator.com/item?id=5322639 https://news.ycombinator.com/item?id=5322639 For your convenience, I'll quote the most relevant part of the story: > One day, I was tracing through the OS code that handled a context switch and was surprised to find a bit of code that looked up the 32-bit creator code of the current application and compared it to 'WORD'. What the heck is this? I wondered. Turns out it was a hack added by the OS engineers at Apple to keep some other hacks in Microsoft Word working. If I recall correctly, they had to determine if Word was getting switched in or out so they could enable or disable the necessary hacks. So, in effect, they had a hack that would live-hack the OS to add hacks for Word's hacks and then live-unhack the hacks for everything else. > I mean, when you're hacking the system to hack the system on behalf of someone who already hacked the system but for an older version of the system that's no longer there, now you're doing some hacking.