[MU4 Issue] Musescore UI not in System Default language

[teetow]

Describe the bug
Musescore shows the incorrect language by default, not respecting its own setting "System Default."

To Reproduce
Steps to reproduce the behavior:

1. Go to Edit > Preferences
2. Verify "Language" set to "System Default" (English in my case)
3. Note that the Musecore UI is in Swedish, which is not my selected Display Language (see screenshots)
4. Silently wonder why every single multiplatform app gets this wrong

Expected behavior
Musescore UI being in English, as per its Language setting

Screenshots

Windows Display Language setting

Platform information

• OS: Windows 10

Additional context
As mentioned, this is a common screwup in applications where devs mistakenly interpret User Regional formatting settings (stuff like date and time formatting) to mean System Language. Please be one of the good guys here.

[cbjeukendrup]

I'm afraid this might be a Qt problem. We get the system language from Qt, using QLocale::system().uiLanguages().
Although Qt intends that this is the correct way to retrieve the display language, we might try another way.

[teetow]

Hmm. I whipped up a quick test app (in PyQt5, granted) and it gave me the following values for the settings I could scrounge up from various SO answers:

So, the only place where Swedish shows up is indeed in QLocale::system()::uiLanguages(). Now, I can't really make heads or tails of all the stuff in languageService.cpp but I'm seeing references to languageCode which makes me believe that (at least on my machine) the last code in that list gets picked as the assumed system language.

Good news is, you have two other methods that (again, on my machine) yields English -- QLocale.system().language() and QLocale.system().name(). So maybe there's some hope.

[Tantacrul]

@cbjeukendrup - can you prioritise (4.x, post-beta, release etc.)? If we think it's an easy, quick fix, then release would be appropriate.

[cbjeukendrup]

@teetow There's a small chance that this is fixed by #14701. Could you please try the builds from that PR?

[teetow]

@teetow There's a small chance that this is fixed by #14701. Could you please try the builds from that PR?

I did, and the issue is no longer present.

For what it's worth, it's also not present in the build currently on MuseHub (info pasted below).