[Ygg2]

Say what you want but for modern UI localization and accessibility are part of minimum feature set. Those two massively increase complexity (UTF8, IME, Braile, Text to speech, etc.)

The big issue I'm talking about is cross OS UI Toolkit. Great your UI supports IME on Windows and Mac. Now do that for Linux, BSD, etc.

[pjmlp]

First they have to decide what distribution actually matters for the desktop, out of hundreds that get forked for frivolous reasons.

And yes accessibility and localisation were already a thing in Windows 3.x, classical Mac OS, OS/2,...

[Ygg2]

I'm talking about accessibility and localization as part of a GUI toolkit.

Take localization. Any doofus with CSV and regex can localize a binary. How do you localize dynamic things like "Hi (Sir) PJMLP, you have (0 unread messages)"?[1]

In JS I can always Intl.PluralRules. Where are my Plural rules in say C#'s Avalonia (or whatever GUI is hot in C# these days, I can't keep track)?

The issue isn't a checklist; it's a quality of availability [2]. The complexity there is essential, because languages are complex beasts, and mitigations for disability are getting better and hence more complex[2].

[1] Why is localizing this a problem? Some languages are language neutral, some have honorific speech, which changes other words, and some have different ways of counting (Hello Welsh. Nice that you have ordinals for zero, one, two, few, many, and more), some have genders, some don't, some have but don't use it in some cases, ad infinitum.

[2] There is a huge Mariana Trench in the quality of accessibility for software that offers a magnifying glass and software that offers text-to-speech.