Re: Use cases for post-redisplay hooks

[Stefan Monnier <monnier@iro.umontreal.ca>]

> I am using a slightly modified version of Emacs that has what
> I call a `window-start-end-hook`, which lets me draw overlays on just the
> visible window every command loop.  I needs more work, but that is the
> general idea of the modification.

Could you clarify what you use it for?

Also is it run after redisplay?  If so, how does it work?  I mean how do
you add overlays *after* redisplay?  Do you trigger a second redisplay
right after the first, or is it simply that your overlays don't affect
the display?

> There are certain movements of point that are not covered by the
> `window-scroll-functions` hook, so that hook cannot be used reliably for the
> above-mentioned purpose.

Not sure what point has to do with window-start-end-hook.

> And, the hook *may* run more than once each command loop, leading to
> potentially wasted time spent running an overlay function that will
> need to run again anyway before the display cycle finishes.

Is that a problem in practice?


        Stefan