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bug#15783: 24.3; posn-at-x-y is relative to the buffer area, posn-at-poi
bug#15783: 24.3; posn-at-x-y is relative to the buffer area, posn-at-point is relative to the text area.
Fri, 17 Nov 2017 11:32:45 +0200
> From: Alex <address@hidden>
> Cc: 椎野 裕樹 <address@hidden>,
> Date: Fri, 17 Nov 2017 01:46:36 -0600
> >> On Emacs 22 and 23, both functions are relative to the buffer area
> >> including the header line. It's fine.
> > That caused much more grave bugs.
> What kind of bugs did it cause?
See bug#7390, for example.
> It's pretty jarring to have the following return nil when a
> header-line is present:
> (let ((x-y (posn-x-y (posn-at-point))))
> (equal x-y (posn-x-y (posn-at-x-y (car x-y)
> (cdr x-y)))))
It's less than ideal, but the alternatives are worse.
> I noticed this since an Emacs package uses posn-x-y and posn-at-x-y to
> try to preserve the point's screen coordinates before and after a
> scroll. With a header-line, this puts the point one row too high.
> It should probably just let-bind `scroll-preserve-screen-position',
> Still, the above is pretty counterintuitive. If nothing else, I
> think this incompatibility should be highlighted.
Not sure what "highlighted" means in this context. What are you
suggesting in practice?
> P.S. I noticed that the manual for `posn-at-x-y' states that the WHOLE
> argument affects both X and Y, but the docstring only states that X is
Feel free to fix such discrepancies without any discussion, and