bug#14604: 24.3.50.1; Possibly incorrect behaviour of frame-selected-window

[E Sabof]

On Thu, Jun 13, 2013 at 3:35 PM, Stefan Monnier <monnier@iro.umontreal.ca> wrote:

> This works on 24.3, but on trunk all windows will be shown as "selected".
> (setq-default
>  mode-line-format
>  '(:eval (if (eq (frame-selected-window)
>                  (selected-window))
>              "selected"
>              "not-selected")))

Indeed this doesn't work any more.  This was one of the very few places
where (eq (frame-selected-window) (selected-window)) was nil, and this
"invariant" is presumed at various places in the C code, so it was
a bug.

BTW, this worked in Emacs<24.3 if you wanted to highlight every frame's
selected-window, but not if you wanted to highlight "the one and only
selected-window".  For single-frame settings, there's no difference,
of course.

There is no alternative, yet.  We should probably provide some ad-hoc
primitives (call them maybe display-selected-window and
display-frame-selected-window) which return something like "the window
that was selected when we entered redisplay".


        Stefan

 

FWIW, the below seems to be working, although it still feels like an omission.

Evgeni

(defvar user-selected-window nil)

(defun register-user-location ()

  (setq user-selected-window (selected-window)))

(add-hook 'post-command-hook 'register-user-location)

(setq-default
  mode-line-format
  '(:eval (if (eq user-selected-window (selected-window))
              "selected"
              "not-selected")))