In !2051, we switch back to real locale before setting the label text,
however, according to nl_langinfo's manpage, the returned pointer could
be invalid after switching locale or creating new locale, so the program
may crash.
To fix this, we save the result before switching locale, so we won't
access the invalid pointer after switching locale.
Row subtitles in Settings are typically a description of the main label or setting.
You can see this in Mouse & Touchpad, Privacy, Sharing, and Wi-Fi.
For the System panel we did something a bit different and used the subtitle to show
the status of each panel.
Given the standard use of subtitles elsewhere, this feels a bit surprising which,
as a result, makes the panel harder to read. I think that a standard description
would probably also be more useful than the current labels.
Mockups https://gitlab.gnome.org/Teams/Design/settings-mockups/-/blob/master/system/system-panel.png?ref_type=heads
This also removes the thin CcSystemPage abstract class because it was
only introduced to add the support for dynamic System row subtitle. Now
this abstraction is no longer necessary.
Fixes#2776
The Formats preview tries to find the measurement format of the locale
to preview, and then displays it. However, it displays the text in the
default locale, instead of in the real current locale, as newlocale ()
with base = (locale_t) 0 will use the default locale.
This is fixed by switching back to the real locale before setting the
label text.
Fixes#2458
Part-of: <https://gitlab.gnome.org/GNOME/gnome-control-center/-/merge_requests/2051>
"Language" and "Formats" rows from the "Login Screen" section
have the same mnemonics of their counterparts from the "Your Account"
section. Use other letters for mnemonics to fix that.
