bug#32839: 27.0.50; recenter doesn't redisplay

[Juri Linkov]

>> I grepped for window-scroll-functions, and see that the current situation
>> is quite bad:
>> 
>> 1. tabulated-list-window-scroll-function is not called on 'C-u -1 C-l'
>>    when the last window line is fully visible, so it doesn't adjust
>>    the width for display-line-numbers in this case.
>
> A bug report with a recipe would be appreciated.

The recipe is essentially the same as for this bug report,
but more complicated.

>> probably at the same time when post-command-hook is called.
>
> That hook is not called from the display code.  But in any case, if
> post-command-hook is what you want, just use it.  Why do we need
> another hook at the same place?  It sounds redundant.

If window-scroll-functions can't be fixed, then indeed a workaround
is to remember an old value of window-start in pre-command-hook,
and compare it with a new value of window-start in post-command-hook.