Re: help-window-select and info-lookup-symbol

[Helmut Eller]

* martin rudalics [2009-07-21 15:27+0200] writes:

>> (defun slime-close-popup-window ()
>>   (when slime-popup-restore-data
>>     (destructuring-bind (popup-window selected-window old-buffer)
>>         slime-popup-restore-data
>>       (bury-buffer)
>>       (when (eq popup-window (selected-window))
>>         (cond ((and (not old-buffer) (not (one-window-p)))
>>                (delete-window popup-window))
>>               ((and old-buffer (buffer-live-p old-buffer))
>>                (set-window-buffer popup-window old-buffer))))
>>       (when (window-live-p selected-window)
>>         (select-window selected-window)))
>>     (kill-local-variable 'slime-popup-restore-data)))
>>
>> popup-window is the window that displays the help content at W2.
>> selected-window was selected at W1.
>> old-buffer was the buffer associated with popup-window at W1.
>
> How do you get the `old-buffer' and `popup-window' values in general?
> By comparing window configurations before and after `display-buffer'?
> My code included for every window a variable telling whether that window
> was split off by `display-buffer' or which buffer the window displayed
> before it was "used" by `display-buffer'.

We do it by walking windows before and after display-buffer.  I guess
that window-config objects also contain the information it's just not
accessible from Lisp.

>
> I recall it proved very nasty to save the old buffer value when the
> window is re-used again by `display-buffer' because I had to avoid that
> a "valuable" non-help content buffer value would get overwritten by the
> "uselss" value of a help-content buffer.

That's the code that stashes the data into the buffer-local variable:

(defun slime-display-popup-buffer (select)
  "Display the current buffer.
Save the selected-window in a buffer-local variable, so that we
can restore it later."
  (let ((selected-window (selected-window))
        (old-windows))
    (walk-windows (lambda (w) (push (cons w (window-buffer w)) old-windows))
                  nil t)
    (let ((new-window (display-buffer (current-buffer))))
      (unless slime-popup-restore-data
        (set (make-local-variable 'slime-popup-restore-data)
             (list new-window
                   selected-window
                   (cdr (find new-window old-windows :key #'car)))))
      (when select
        (select-window new-window))
      (current-buffer))))

Helmut.