How do you Add Languages to Spellchecker?

[andrejapotic]

I was wondering how spellchecker chooses which language to show in the context menu. It seems to have its own list, that is separate from Windows system languages and also Edge languages, so is there a way to programatically add new language options? Does it show languages based on location?

WebView2 is being used as a Text box in my project. Thing is, on some PC's spellcheck displays our native language (Serbian), while on others it does not and only English is available. The weirdest thing is that on some computers there is no Serbian language installed (neither Edge nor Windows) but spellchecker displays it as an option (again, not on all computers, some only display English no matter what I do).