bug#34476: fluffy whitespace in the mode-line, despite it running off the screen

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: contovob@tcd.ie,  34476@debbugs.gnu.org
> Date: Tue, 29 Dec 2020 16:07:50 +0100
> 
> I was also not quite sure of the selected_window itself -- can the
> mode line be updated while another window is selected?

The function display_mode_line doesn't produce the updated mode-line
contents for the selected window, it produces it for the window passed
as its first argument W.  So instead of this:

          && window_body_width (XWINDOW (selected_window), false) >=

I think you should use this:

          && window_body_width (w, false) >=

> > I understand the difficulty of doing TRT, but perhaps we should at
> > least document this limitation, so that users don't expect too much
> > from this feature, and we don't get bug reports that will be hard to
> > fix?
> 
> Yup; will do.

Thanks.