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: Daniel Mendler <mail@daniel-mendler.de>,  73050@debbugs.gnu.org
> Date: Sun, 08 Sep 2024 09:51:41 +0300
> 
> >> This is only a minor issue. After enabling `tab-bar-mode' when hovering
> >> with the mouse over the `tab-bar-separator' space, an empty tool tip
> >> will be shown after a short delay.
> >>
> >> To reproduce:
> >>
> >> 1. Start emacs -Q
> >> 2. M-x tab-bar-mode
> >> 3. Move the mouse pointer over the space right after the "*scratch*" tab
> >>
> >> Would it make sense to somehow prevent displaying blank tool tips, e.g.,
> >> via the following advice? Or maybe blank tool tips could be prevented on
> >> the tab-bar level?
> >>
> >> (defun x-show-tip-adv (str &rest _) (string-blank-p str))
> >> (advice-add #'x-show-tip :before-until #'x-show-tip-adv)
> >
> > Juri, can we prevent such empty tooltips from being shown by tab bar?
> 
> 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?