bug#38013: [PATCH] Rectangular region selection with mouse

[Eli Zaretskii]

> From: Mattias Engdegård <mattiase@acm.org>
> Date: Mon, 18 Nov 2019 19:08:24 +0100
> Cc: rudalics@gmx.at, 38013@debbugs.gnu.org
> 
> Here is an updated patch that makes the selection work better with characters 
> that aren't a multiple of the standard font width. 

Thanks, a few minor comments:

> +@defvar fine-grained-mouse-movement

I think this variable's name should start with "mouse-".  Like
mouse-fine-grained-movement or something.

> +    (setq fine-grained-mouse-movement t)

What happens if this function signals an error? won't
fine-grained-mouse-movement be left at its non-nil value?