Re: "after" variable watchers

[Eli Zaretskii]

> Cc: emacs-devel@gnu.org, monnier@iro.umontreal.ca, npostavs@gmail.com
> From: martin rudalics <rudalics@gmx.at>
> Date: Mon, 24 May 2021 10:48:29 +0200
> 
>  > these values are needed by redisplay, and calculate them only then?
> 
> If a specified value does not fit, we should be able react in different
> ways:
> 
> - When an application asks for a window size that is not large enough to
>    accommodate its decorations, we should be able to reject that request
>    and signal an error.
> 
> - When the WM shrinks our frame so that a particular window is not large
>    enough to include all of its decorations, we have to comply and do
>    something reasonable to make that window display its contents orderly.
> 
> The display engine is not able to distinguish these cases.  And even if
> it were, how should it react in the first case?

I believe the idea was to run the same function(s) you intend to call
from the watcher at redisplay time.  So if your functions are able to
figure this out, so will redisplay.