bug#59862: quit-restore per window buffer

[Juri Linkov <juri@linkov.net>]

Martin, do you agree with this?  I tested this patch for a long time.

> 1. C-x 4 d RET C-h C-t q q         -- the bottom window is NOT deleted
> 2. C-x 4 d RET C-h C-t C-x k RET q -- the bottom window is deleted
> 3. C-x 4 d RET C-h C-n C-x k RET q -- the bottom window is NOT deleted
>
> The accidental difference between the last two is that the former uses
> `switch-to-buffer' whereas the latter uses `pop-to-buffer-same-window'.
>
> The root of the problem is that displaying a buffer in an existing
> window, or quitting a buffer in an existing window overwrites its
> window parameter `quit-restore', and thus invalidates the history of
> how the first window was displayed.
>
> A partial fix that solves only the first test case above is at least
> not to overwrite `quit-restore' on quitting other buffers in the same
> window:
>
> diff --git a/lisp/window.el b/lisp/window.el
> index a11293d372a..e3b057599d5 100644
> --- a/lisp/window.el
> +++ b/lisp/window.el
> @@ -5275,14 +5276,14 @@ quit-restore-window
>  	(set-window-prev-buffers
>  	 window (append (window-prev-buffers window) (list entry))))
>        ;; Reset the quit-restore parameter.
> -      (set-window-parameter window 'quit-restore nil)
>        ;; Select old window.
>        ;; If the previously selected window is still alive, select it.
>        (window--quit-restore-select-window quit-restore-2))
>       (t
>        ;; Show some other buffer in WINDOW and reset the quit-restore
>        ;; parameter.
> -      (set-window-parameter window 'quit-restore nil)
>        ;; Make sure that WINDOW is no more dedicated.
>        (set-window-dedicated-p window nil)
>        ;; Try to switch to a previous buffer.  Delete the window only if
>
> But the proper fix for other problems would be to replace the window
> parameter `quit-restore' currently shared by all buffers in the same window
> by a stack where every window buffer should keep own quit-restore data.
> There is already such a stack in `window-prev-buffers', so a possible
> solution would be to add quit-restore data to each buffer
> in window-prev-buffers.
>
> Alternatively, it would be nice to have an option that would prevent
> overwriting the initial value of the window parameter `quit-restore',
> thus `quit-restore-window' could delete the window regardless of
> how many buffers were displayed in that window, like it does in case
> of dedicated windows.