bug#61337: 29.0.60; Setting frame-title-format makes Emacs to steal focus

[Eli Zaretskii <eliz@gnu.org>]

> Cc: 61337@debbugs.gnu.org
> Date: Thu, 09 Feb 2023 16:15:39 +0800
> From:  Po Lu via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Óscar Fuentes <ofv@wanadoo.es> writes:
> 
> > Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text
> > editors" <bug-gnu-emacs@gnu.org> writes:
> >
> >> If you set `icon-title-format' to the same as `frame-title-format', and
> >> in addition apply this patch:
> >>
> >> diff --git a/src/xfns.c b/src/xfns.c
> >> index 3a129211463..7f1128399a8 100644
> >> --- a/src/xfns.c
> >> +++ b/src/xfns.c
> >> @@ -2317,7 +2317,7 @@ x_implicitly_set_name (struct frame *f, Lisp_Object arg, Lisp_Object oldval)
> >>  x_set_title (struct frame *f, Lisp_Object name, Lisp_Object old_name)
> >>  {
> >>    /* Don't change the title if it's already NAME.  */
> >> -  if (EQ (name, f->title))
> >> +  if (Fstring_equal (name, f->title))
> >>      return;
> >>  
> >>    update_mode_lines = 38;
> >>
> >> does the problem go away?
> >
> > Yes!
> 
> Thanks.
> 
> Anyone know if this is ok for Emacs 29?

Which part? the change in xfns.c is fine (it just makes the code
slower, so perhaps test EQ first and Fstring_equal if EQ doesn't
return non-zero), but if someone sets icon-title-format in a way that
produces a different string from what frame-title-format does, it will
not work.  And forcing these two formats to produce the same strings
is definitely NOT okay, not for emacs-29, not ever.

However, to tell the truth, I don't really understand the phenomenon
being complained about in this case.  The original report says: "the
z-order is not altered", whereas the conclusion of the analysis is
"KWin seems to treat this as Emacs asking to be focused".  Would you
please describe the problem in easier-to-understand terms and use the
user-facing behavior instead of technical terms like z-order, so that
I could at least make up my mind whether this issue is serious, and
perhaps think about alternative solutions?  E.g., I don't yet
understand why returning early in x_set_title should help here, and
how.

Thanks.