bug#69942: 30.0.50; Fontification of radio-button widget labels

[Stephen Berman]

In bug#69941 I reported a faulty fontification of radio-button widgets
and noted in passing that the labels associated with the radio buttons
also have unexpected faces, namely, the widget-inactive face regardless
of whether the associated radio buttons are inactive or active (except
for the label of a radio button that has been pressed, which has the
default face).  While the faulty fontification discussed in bug#69941
appears to be a real bug, the widget-inactive face assigned to
radio-button labels is apparently by design -- it was present in the
initial commit of the widget library.  But this seems to me to have been
a UX mistake, since it effectively ignores the semantics implied by the
name widget-inactive.  I think a less surprising UI would be for the
labels to be fontified according to the widget's activation state:
default face when the widget is active and widget-inactive face when
it's inactive.  The attached patches provide two possible
implementations of this UI.

The first patch makes the change unconditionally, treating the current
fontification as a UI/UX bug.  But it may be argued that this aspect of
the widget UI should not be unconditionally changed, since it was
apparently a deliberate design choice and there have been (AFAIK) no
complaints about the semantic discrepancy till now.  The lack of
complaint could be because the widget-inactive face inherits the shadow
face, so it is not sharply different from the default face.  But if one
uses a very different face (as I did for illustrative purposes in
bug#69941), the inconsistency is very obvious and (IMO) jarring.
Nevertheless, to allow keeping the current fontification, the second
patch conditionalizes the change from the current fontification by means
of a user option (with the default being the current fontification).

Is either of these changes acceptable?

widget-radio-nocust.diff
Description: Text Data

widget-radio-cust.diff
Description: Text Data

In GNU Emacs 30.0.50 (build 3, x86_64-pc-linux-gnu, GTK+ Version
 3.24.38, cairo version 1.18.0) of 2024-03-22 built on strobelfs2
Repository revision: c1530a2e4973005633ebe00d447f1f3aa1200301
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101009
System Description: Linux From Scratch r12.0-112

Configured using:
 'configure -C --with-xwidgets 'CFLAGS=-Og -g3'
 PKG_CONFIG_PATH=/opt/qt5/lib/pkgconfig'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBSYSTEMD LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY PDUMPER
PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS
TREE_SITTER WEBP X11 XDBE XIM XINPUT2 XPM XWIDGETS GTK3 ZLIB