Yep, Windows XP icons were designed and produced on a Mac in FreeHand.

Microsoft was our first paying client back in 1997: we made the icon suite for Outlook Express on Mac OS 9. It was the email counterpart to Internet Explorer 5.

https://news.microsoft.com/source/1998/01/06/microsoft-announces-march-availability-of-office-98-macintosh-edition/
https://techhub.social/@maccatalan/114155754052920748

Microsoft Announces March Availability of Office 98 Macintosh Edition - Source

25,000 Hours of Customer Research and Over 1 Million Wish Line Requests Shaped Product Tailored to Macintosh Customer

Source

If you love seeing our early work, including Windows XP, this podcast episode is a great behind-the-scenes look at how it all happened.

There are also links there to the icons, concept sketches, style explorations, and even a TV commercial that featured the work!

https://www.patreon.com/posts/episode-006-old-34485216

@chockenberry i had no idea y’all did this, incredible

@beep Yeah, most people don't know about it. We promoted it at the time, but that was DECADES ago and we barely remember it (I had forgotten the name of Outlook Express!)

Best part of the project was that it prepared us to handle huge client requirements. Like 3,000 emoji:

https://design.iconfactory.com/whatsapp-emoji/

WhatsApp Emoji • Iconfactory Portfolio

The Iconfactory has worked hand-in-hand with the team at WhatsApp to design and produce over 3,000 individual emoji for their popular mobile messaging application. The suite contains expressive, hand-drawn icons in every category of emoji and includes elements from the Unicode 10, 11, 12  and 13 releases. You can learn more about what went into […]

Iconfactory Portfolio
@chockenberry I knew you folks did Big Jobs™, but didn’t realize this was the origin story! COOL
@chockenberry I'll never not be mad Freehand was abandoned.
@jblake @chockenberry I’m still miffed that Aldus ended up with FreeHand (and a bunch of other applications) when it acquired Altsys.
@chockenberry @maccatalan MS was your *first* client? How did you jump into waters that deep so quickly?
@ashkendo @maccatalan By not knowing any better and being confident in our work 😂
@chockenberry wow, goin’ wayback! A factory of goodness.
@chockenberry Some of Dave’s very first concept sketches for Microsoft Whistler (Windows XP) circa 2000. ✍️🤓

@Iconfactory I love the globe with the soap! I’m guessing that was for some kind of Internet parental control?

Edit: Given its proximity to the broom, more likely for a “cleanup” task (e.g. clearing cookies)

@chockenberry That’s very cool. I mostly knew you for making great software for Apple platforms and some nice wallpapers. I was aware that you were also doing design work for others, but I had no idea that you created the Windows XP icons. This blows my mind. It’s one of the most surprising things I’ve learned so far this year.
@chockenberry @maccatalan kind of amazing (or unsettling) that you could paste this paragraph into a Microsoft press release about Copilot AI *today* and it wouldn’t seem out of place.
@chockenberry Makes me very happy that they were drawn in FreeHand specifically.
@chockenberry These are amazing. Undoubtedly my favourite look of Windows and the icons are what made it so! They look so friendly! Wonderful to have access to the details of how it all came about!