Not just luck — Adobe were fighting dirty with a look-and-feel lawsuit against Macromedia for use of tabbed palettes: https://web.archive.org/web/20010516014855/http://www.adobef...
“Adobe's tabbed palette, used throughout Adobe's products, are being copied by Macromedia® in many of its products, including Macromedia® Flash™ 5, Dreamweaver®, FreeHand® and Fireworks® software.”
Compare the infringing tabbed palettes of Flash 5 to the non-infringing (vertically-stacked) palettes of Flash MX:
- https://www.webdesignmuseum.org/old-software/macromedia-flas...
- https://www.webdesignmuseum.org/old-software/macromedia-flas...