bug#17905: 24.3.50; writing with a giant font triggers RTL text entry

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: holtzermann17@gmail.com,  17905@debbugs.gnu.org
> Date: Thu, 03 Jul 2014 15:49:29 -0400
> 
> > If it only shows up when point is in a partially visible line, then
> > the bug is that Emacs lets point be displayed in such a line.
> 
> Probably (tho I don't know why this causes point to be changed).

The display engine is probably confused by what happened, so it does
something utterly inappropriate.  There are situations where redisplay
moves point, but this is not one of them.

> I confirm that point (and the corresponding cursor) is at the
> leftmost position of the partially displayed screen line in that
> case.

That's the immediate cause of the bug, I'm quite sure.  And it goes a
long way back.