bug#17453: Framework extending window functions for Follow Mode (etc.).

[Juri Linkov <juri@linkov.net>]

>>   (add-hook 'isearch-update-post-hook 'recenter)
>>   (add-hook 'replace-update-post-hook 'recenter)
>
> First comment: this sort of thing will wreck Follow Mode, scrolling text
> in the current window rather than point moving forward to the next
> window.

I guess a lot of other customizations will wreck Follow Mode too.

>> How would you do the same without these hooks, using only post-command-hook?
>
> By putting #'recenter into `post-command-hook'?  This should work for
> Isearch, and would work for Replace and Ispell if these two used the
> Emacs command loop.

This will call #'recenter on every command.

> I have indeed put *Choices* at the top of the RH window, to preserve
> sanity.
>
> I committed those changes, including changes to Ispell this afternoon.  I
> think they're close to working fully.

Yes, pretty close.