bug#22048: 25.1; frame title vanishes when speedbar present

[Eli Zaretskii]

> From: David Reitter <david.reitter@gmail.com>
> Date: Sun, 29 Nov 2015 19:14:20 -0500
> Cc: 22048@debbugs.gnu.org,
>  konrad.podczeck@univie.ac.at
> 
> >> x_implicitly_set_name() might not be called in the right context for 
> >> frames 
> >> that are not selected.
> > 
> > That shouldn't happen, normally.  Displaying a frame temporarily makes
> > it the selected frame.
> 
> The buffer was not current in x_consider_frame_title when 
> x_implicitly_set_name 
> is called.
> 
> The consequences then are obvious, as it picks up the wrong 
> Vframe_title_format 
> for the frame.

I'm afraid I don't follow: why does ns_set_name_as_filename need the
buffer to be the current buffer?  It access that buffer through the
frame pointer:

  Lisp_Object buf = XWINDOW (f->selected_window)->contents;
  [...]
  filename = BVAR (XBUFFER (buf), filename);
  name = BVAR (XBUFFER (buf), name);

I don't see where it needs to access current_buffer.

Can you tell which part(s) of this don't work, and why?

Thanks.