[Ygg2]

Sure. Show me how Windows 3.* supported Unicode, i18n (internationalisation), l10n (localisation), a11y (accessibility), with special focus on CLDR plural rules.

Which will be interesting since Unicode 1.0 came around 1991. And CLDR in 2003. And Windows 3.x came in 1990.

I'm not saying it is impossible, just highly unlikely MSFT implemented those as early in 3.x. They could have taken part in those early efforts.

[pjmlp]

If you are so keen in Windows 3.x, remember before standards each OS did its own thing, and I can gladly show you the proprietary APIs used by Windows 3.x.

I imagine you never coded for it.

[speed_spread]

None of the things you mention would have been impossible to integrate in native GUI. They're platform features.