bug#16129: 24.3.50; Emacs slow with follow-mode when buffer ends before last window

[Stefan Monnier]

> Great.  I would suggest that it should be implemented so that the actual
> test could be written in elisp.

Yes, clearly.

> In the Follow mode case, the test should be that the buffer is in
> Follow mode and that it's not the first window.

If we can avoid running Elisp code redisplay, it's always better.
So since the behavior is not the same for all windows of a buffer, maybe
a window-parameter is a better option than a buffer-local value.

> In the simplest form it could be a symbol, nil for "no", t for "yes", and
> for all other cases call the function it is bound to. Of course, one could
> make it into a hook, so that more than one mode could have a say, but I
> think that might be overengineering it a bit...

A single function is sufficient since you can "share" it with
add-function.


        Stefan