> 
> FWIW, I don't see any problem with that, because users won't expect
> that to happen anyway.
Can you clarity “what to happen”?

I think it’s quite common to have a very long single input sequence,
especially when I’m using some input method package that
does word hint based on context. I basically enter a whole phrase
or even sentence at once. 

I’ve done it with my hack (push forward the overlay input method
uses) and it doesn’t block remote changes. It works with the
builtin Chinese input method, and also a few external package I’ve
tested. I don’t know if there's any problem with this approach.

> Hmm... That's clearly a problem.  I can imagine some reasons why we do
> that, but I'm not sure they're good enough.  This probably deserves
> a `M-x report-emacs-bug`.
I don’t know, will it cause more problem if the input method
actually trigger *-change-functions during halfway input?
At least for my use case, that means the halfway input sequence
is also synchronized to other peers and that doesn’t make much
sense — so I’ll have to filter it anyway.

I think maybe the “correct” way is to display input sequence not
as text in the buffer (conceptually they aren’t yet).