bug#16497: 24.3.50; `move-to-column' ignores invisible text at the beginning of the line, which create problems when using string-rectangle

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: Eli Zaretskii <eliz@gnu.org>,  16497@debbugs.gnu.org
> Date: Mon, 20 Jan 2014 13:14:37 -0500
> 
> > emacs -Q
> > M-: (insert "abc") RET
> > C-a
> > M-: (put-text-property (point) (1+ (point)) 'invisible t) RET
> > C-a
> > C-a
> > C-a
> 
> > ... !  See the point moving from b to c and back again.
> 
> It's probably due to the post-command processing which tries to move
> point outside of invisible regions and to pretend that invisible regions
> don't exist at all (and paying attention to stickiness so that it
> prefers text positions where `invisible' won't be inherited).

Indeed, and the direction where it moves point depends on the previous
command and/or movement direction.

It's a murky area full of semi-working heuristics.