Re: Why mouse-1/2/3 ?

[Michael Welsh Duggan <mwd@md5i.com>]

ndame <ndame@protonmail.com> writes:

> I don't use the mouse in emacs at all, but when browsing info mouse-2
> caught my eye.
>
> Why emacs calls these mouse-1, 2 and 3? Wouldn't it be more user
> friendly to say left mouse button, middle mouse button and right mouse
> button?
>
> I checked what terminology Gnome uses:
>
> "Press the right mouse button on any local folder"
>
> https://help.gnome.org/users/shares-admin/stable/tool-getting-started.html.en_GB

It comes straight from X11 terminology.

1 = left
2 = middle
3 = right
4 = scroll wheel up
5 = scroll wheel down
6 = scroll wheel left (yes, really)
7 = scroll wheel right
8 = 4th button (browser back)
9 = 5th button (browser forward)

In point of fact, Emacs's first scroll-wheel support was on Windows.  I
know because I wrote it at the time.  (This was in the '96-'97
timeframe.  I didn't even have a mouse with a wheel at the time.  I had
to borrow a coworker's in order to test the code.)  At the time, I used
a new event, mouse-wheel, for the mouse-wheel event.  I don't know if
X11 supported a mouse wheel at this time.  Mainline (X11) emacs did not
need to change to support a mouse wheel once X11 had support for it: it
was just a new button number.  The symbol was just a concatenation of
"mouse-" and the button number.  Later work was done to unify NTEmacs
and mainline emacs, and the Windows-specific stuff changed to be more
like the X11 version.

One major advantage of the numbered naming system is listed above: the
code in emacs didn't need to change in the slightest when new buttons
were added.

-- 
Michael Welsh Duggan
(md5i@md5i.com)