bug#17047: 24.3.50; visual-line-mode + org-mode + C-f makes cursor jumps to unexpected position

[Eli Zaretskii]

> From: Nicolas Richard <theonewiththeevillook@yahoo.fr>
> Cc: 17047-done@debbugs.gnu.org
> Date: Mon, 24 Mar 2014 10:41:07 +0100
> 
> > Note that moving cursor to the "f" of "file" from the left will get
> > you to position 8, while moving there from the right will get you to
> > position 10.  But this is a separate "feature".
> 
> This is not unexpected I think. It would be nice to have a visual clue
> about which side of the invisible text we stand, but I have no idea what
> kind of clue it should be. Is that worth a wishlist bug anyway ?

The clue you mention is not what bothers me.  What bothers me is that
the same position of the cursor corresponds to 2 different text
positions, and you can only get to one of them, depending on the
direction of the cursor motion.  From the left, you get positions 7,
8, 11, 12, ...  From the right, you get 12, 11, 10, 7, ...  The cursor
is positioned on the same character for both 8 and 10.

The only justification for this "feature" is that otherwise you
couldn't have inserted text before the invisible portion.

> > Also note that this situation is one of the small number where
> > visual-order-cursor-movement works differently from the default
> > logical-order one, even though there's no bidirectional context
> > anywhere in sight.  And that is also a feature.
> 
> Just for the record, the difference is that no matter if we come from
> left or right, we get to position 10.

Indeed, because it goes by characters that are actually displayed, and
the character at position 8 is not.