Re: Let mode-line packages distinguish the selected-window

[Stefan Monnier]

> To deal with this the packages mentioned above resort to using several
> hook functions and advice to keep track of "the" selected window and
> then they do something like:

AFAIK since Emacs-24.4 only one hook is needed:

    (add-function :before pre-redisplay-function
                  (lambda (_)
                    (setq remembered-selected-window (selected-window))))
or
    (add-hook 'pre-redisplay-functions
              (lambda (_) (setq remembered-selected-window (selected-window))))

> Because keeping remembered-selected-window up-to-date involves several
> hooks and advises this is rather ugly and fragile.

With `pre-redisplay-function(s)` is should be "easy and reliable".

> In summary, please add a way for functions that format elements of the
> mode-line to determine whether these elements are going to be used in
> the selected or some other window.

Despite what the above may suggest, I fully agree: while it's now easy
to "roll your own", this is a common need and we should provide this
info directly.


        Stefan