It's kind of interesting, when you compare WinAPI to classic Mac Toolbox, how incredibly similar their core concepts are.

Especially when you take into account that the first GUI application MS made was Excel for the Macintosh. And then they more-or-less wrote Windows as a runtime environment for porting Excel to PCs.

Not getting into any of that old-school MS-stole-the-GUI flamewar business, I just think it's genuinely historically interesting to note the parallels when you play with each.