Proposal for BiDi in terminal emulators

[Eli Zaretskii via Unicode]

> From: Egmont Koblinger <egmont at gmail.com>
> Date: Thu, 31 Jan 2019 10:28:27 +0100
> Cc: Adam Borowski <kilobyte at angband.pl>, unicode at unicode.org
> 
> On Wed, Jan 30, 2019 at 5:10 PM Eli Zaretskii <eliz at gnu.org> wrote:
> 
> > I think the application could use TAB characters to get to the next
> > cell, then simplistic reordering would also work.
> 
> TAB handling is extremely complicated, because in terminal emulation
> TAB is not a character, TAB is a control instruction (like escape
> sequences) that moves the cursor (and jumps through the existing
> content, if any, without erasing it).

The reordering happens before TABs are converted to cursor motion,
does it not?  If so, their effect on reordering, by virtue of the TAB
being Segment Separator for the UBA purposes, could happen
nonetheless.  Right?