Merge from origin/emacs-29

99efe5c80f9 Fix count of no-op functions (bug#68375)
0c01f97b73c Wrap @pxref of Abbrevs in parentheses (bug#68375)
70a09325d65 ; Fix last change in widget.texi
63411709a8d ; Fix typos
824cf54951c ; * etc/TODO: Add item to make play-sound non-blocking.
4fadbfe300a Add examples to the Widget manual
1bbb610821e Implement missing functions for custom-icon widget
29af214a75a Fix fontification of cgroup2 in fstab (bug#68367)

diff --cc doc/lispref/functions.texi
Simple merge

diff --cc doc/lispref/symbols.texi
Simple merge

diff --cc etc/TODO
Simple merge

diff --cc lisp/cus-edit.el
Simple merge

diff --cc lisp/progmodes/python.el
Simple merge