Re: Window change functions

[Stefan Monnier <monnier@IRO.UMontreal.CA>]

>>  >> +@defvar window-state-change-functions
>>  >> +This variable specifies functions called at the end of redisplay when
>>  >> +window states have changed.  The value should be a list of functions
>>  >> +that take one argument
>>  > If it's run "at the end of redisplay", then I think it's too late: those
>>  > hooks will often want to change something visual, and they will want it
>>  > to appear right away, so it should be run just *before* redisplay.
>> Note that 'window-size-change-functions' are currently already run
>> right in the middle of redisplay.  Often, window sizes are correct
>> only *after* redisplay.  Think of minibuffer window resizing or
>> changes in the fringes, margins or modeline sub-structures.  But a
>> final word on the location of the call will have to be told by Eli.
> I don't think I can utter that final word, primarily because I don't
> understand Stefan's concerns.  Stefan, could you please elaborate?

For example, I have a window-size-change-functions which I use to
re-balance windows (using balance-window-area) after a frame resize.
It doesn't care about the exact window sizes when it's called, so having
correct window sizes when it's called is not necessary.  OTOH redisplay
will need to happen right after it was run, because it changes
window sizes.  So the best time to run it is right before redisplay.


        Stefan