Re: master 101bbd1392: Add support for pinch gestures to the XI2 build

[Eli Zaretskii]

> From: Po Lu <luangruo@yahoo.com>
> Cc: emacs-devel@gnu.org
> Date: Sun, 26 Dec 2021 18:51:21 +0800
> 
> DX and DY are represented in an imaginary unit where 1.0 is the
> horizontal width and vertical height of the touchpad (or more precisely,
> depedent touch device, which might include Wacom tablets if their
> drivers are configured in a special way) respectively.

This should be documented.  But I wonder how these two values are
useful, if their units are not pixels and not anything that can be
converted to pixels?