bug#21333: 25.0.50; window-size-change-functions not called after mini-window resize

[Pip Cet]

On Tue, Aug 25, 2015 at 7:25 AM, martin rudalics <rudalics@gmx.at> wrote:
>>> Naively spoken it's obvious that when you shrink the minibuffer you show
>>> more lines in the window above and ‘linum-mode’ has to add numbers for
>>> those lines.  And when you enlarge the minibuffer, ‘follow-mode’ will
>>> lose some lines at the bottom of the left window and has to show them at
>>> the top of the right window.
>>
>> In well-behaved modes this happens automatically, as part of
>> redisplay.
>
> Via ‘pre-redisplay-function’?

Well, we have `pre-redisplay-functions', with an s, defined in
simple.el, and I've attached some (trivial) code that takes things a
little further and calls a normal hook when a window's size changed.

> How does a well-behaved mode detect
> whether it has to make "this happen automatically"?  By walking all
> windows and checking whether their sizes, start and end positions
> changed, I suppose.

That's what my code does. I thought I could get away with using the
arguments passed to pre-redisplay-function to limit which windows to
check, but that doesn't work when we "goto retry" and re-run
pre-redisplay-function. I will study the code in xdisp.c further and
see whether I can understand what the purpose of must_finish is.

>> I'd say, don't set the "size changed" flag unless the size really
>> changed.
>
> Sure.

Patch attached (no news on the paperwork so far). I'm not sure
precisely which properties should be checked for change, though.

I do think it would be best not to use set-window-configuration in
restoring state after exiting the minibuffer at all.

> Alternatively, Fset_window_configuration could run a modified version of
> ‘compare-window-configurations’ to compare the current configuration
> with the one to be restored and restore the old configuration iff these
> differ.  I'm not sure whether this would be any cheaper, especially when
> the configuration does change frequently.

I think it would be better to do this explicitly, even if we have to
compare all properties.

Thanks again to both of you,
Pip

emacs-via-redisplay-014.el
Description: Text Data

0001-Only-set-FRAME_WINDOW_SIZES_CHANGED-if-necessary-213.patch
Description: Text Data