Re: :align-to space spec and line wrap

[Eli Zaretskii]

> From: Qiantan Hong <qthong@stanford.edu>
> Date: Sun, 30 Apr 2023 10:48:35 +0000
> 
> It turns out that similar same thing also happen for horiontally
> scroll. Once I horizontally scroll to the right, the space align to
> somewhere in the middle of the screen, rather than visually to the
> right.

Of course.  And for the same reason: the columns are still counted
from the (now invisible) left edge of the window, i.e. from the very
first column of the buffer text.

> I understand how current implementation will exhibit such behavior.
> Is such behavior desired? The info node "40.16.3 Pixel Specification
> for Spaces" says that `:align-to' specifies positions relative to
> "text area", which is defined as a concept about window geometry
> ("29.1 Basic Concepts of Emacs Windows"). Therefore, I think the
> desired behavior is to align to visual positions in the window.

Text area begins where text begins, even if that text is not visible
due to hscroll.  You are interpreting that text in the manual too
literally, and try to apply it to situations where the left edge of
the text area is not visible.

> I'd also argue this is also more useful in practice as it allows one
> to display some text in desired horizontal position in the window.
> I've yet to encounter a use case where the current buffer
> position-based behavior is desired. It's a display property, after
> all, and is probably more commonly used for displaying stuff!

Sorry, it's too late to change these basics of the window geometry, as
they have existed for the last 23 years.