Re: "after" variable watchers

[martin rudalics <rudalics@gmx.at>]

 >> window_updeco_window is called indirectly from all places that change a
 >> window's decorations, font or size.
 >
 > Would it make sense to call it more lazily, e.g. as part of redisplay
 > (basically, the watchpoints would just set some dirty bits and then at
 > the beginning of redisplay you'd then run `window_updeco_window` on
 > those windows with the dirty bit set)?

That was my first approach given our current implementation of watch
points.  I spent a couple of weeks on it but it didn't really work out.
Between the time a variable is set and the time the setting is applied,
the "realized" values would be inaccurate.  These values are, however,
needed in too many places before we start redisplaying a window.

I do not want to exclude that such a lazy approach could work.  But it
would require more profound changes to the way window sizes and
decorations are processed than the approach based on "after" variable
watchers.

martin