bug#73050: 30.0.90; Empty tool tip when hovering over tab-bar separator

[Eli Zaretskii <eliz@gnu.org>]

> From: Juri Linkov <juri@linkov.net>
> Cc: mail@daniel-mendler.de,  73050@debbugs.gnu.org
> Date: Sun, 08 Sep 2024 19:40:18 +0300
> 
> >> Maybe this unasked-for default fallback is not needed after all:
> >>
> >> diff --git a/src/xdisp.c b/src/xdisp.c
> >> index f9a10267bad..18834c6b781 100644
> >> --- a/src/xdisp.c
> >> +++ b/src/xdisp.c
> >> @@ -15155,8 +15155,6 @@ note_tab_bar_highlight (struct frame *f, int x, int y)
> >>    help_echo_object = help_echo_window = Qnil;
> >>    help_echo_pos = -1;
> >>    help_echo_string = AREF (f->tab_bar_items, prop_idx + TAB_BAR_ITEM_HELP);
> >> -  if (NILP (help_echo_string))
> >> -    help_echo_string = AREF (f->tab_bar_items, prop_idx + TAB_BAR_ITEM_CAPTION);
> >>  }
> >>
> >>  #endif /* HAVE_WINDOW_SYSTEM */
> >
> > Do you remember why was this introduced?
> 
> It was copy-pasted from tool-bar code.

But on the tool bar there are no empty space between buttons.  On the
tab bar, there is.  What I don't understand is why those empty spaces
have tooltips.  Because each tab-bar button has a valid, non-nil
tooltip, so the problem is with the tooltips popped up when the mouse
is between buttons.  Do you understand why this happens?