bug#18793: 24.4; zero width rectangular selection displaces text

[Drew Adams]

> Adding capabilities to the Emacs display that operate on
> sub-character-cell resolution will mean serious complications.  For
> example, what would we do when displaying color Emoji at that place?
> Or what about images?  Or what if the character in question is
> currently highlighted by mouse-face?
> 
> IOW, I'm asking whether these marginal features are worth a serious
> surgery and complications in the display engine, which currently has
> the canvas-based design?

None of what you guys have suggested so far
is a good solution to the problem reported.

I suggested a simple solution that provides
feedback not only that an empty rectangle is
selected but continual feedback about any
rectangle selection.

It's about informing users.  No special
display gimmicks are needed for that.