Re: buffer-modified-tick and text properties

[Eli Zaretskii <eliz@gnu.org>]

> From: JD Smith <jdtsmith@gmail.com>
> Date: Sat, 20 Apr 2024 08:47:42 -0400
> 
> I had hoped to compare a saved and current buffer-modified-tick in a post-command-hook, to tell me whether
> the command that lead to it had modified the buffer text, but this is not a reliable way to do so when text
> properties are being changed as a result of non-edit commands (like motion).

If you want to know only about changes to characters, perhaps
buffer-chars-modified-tick is a better function to use?

Or how about if you explain why the fact that buffer-modified-tick
changes even under with-silent-modifications gets in your way, and
what would you like to do that need that tick to be sensitive to what
with-silent-modifications does?

> Plenty of modes compare the buffer tick against a saved value to infer whether the buffer text has been
> modified since the last update.  That logic will be defeated if other modes make text property changes.  Is
> there a way to inhibit changes in the buffer-tick when you are just changing simple text properties?

You cannot do that without breaking redisplay, because the display
engine uses the tick value to know when it might need to redisplay
portions of a window.  But I'm still uncertain why this presents a
problem, given that we have buffer-chars-modified-tick.  What am I
missing?