Mouse wheel not working with new mouse

Question

I'm running Emacs 25.1.1 on Debian. No particularly elaborate setup.

I recently bought a new mouse, a Logitech MX Anywhere 2S, though I am not using any of the "programmable" features. I simply use the mouse via Bluetooth. I haven't changed anything anywhere.

It works fine in every other application, but in Emacs, when I try to scroll, I get beeps and C-M-( [or C-M-)] is undefined. mouse-wheel-mode is enabled.

The other aspects of the mouse work as expected; I can paste using the middle button, for example.

Any thoughts on how to fix this?

Answer 1

If your mouse wheel rotation is seen by Emacs as keys C-M-( and C-M-) then you presumably need to bind those two keys, to make the wheel work with Emacs.

For example:

(global-set-key (kbd "C-M-(") 'mwheel-scroll)
(global-set-key (kbd "C-M-)") 'mwheel-scroll)

Or whatever command is appropriate for your use (and platform).

But what are your values of these user options (use C-h v)?

• mouse-wheel-down-event
• mouse-wheel-up-event

mouse-wheel-mode uses the values of those two options to construct the keys that it binds to mwheel-scroll.

You might also do this, to find out what keys mouse-wheel-mode has bound to mwheel-scroll: C-h w mwheel-scroll.

Answer 2

;; Fix mouse wheel
(global-set-key (kbd "C-M-(") (kbd "<mouse-4>"))
(global-set-key (kbd "C-M-)") (kbd "<mouse-5>"))

This is a combination of answer: https://emacs.stackexchange.com/a/36036/17985 and some comments, and this: https://emacs.stackexchange.com/a/49083/17985

Answer 3

It may be possible to adjust the mouse's configuration in Emacs, using some available X Window System utilities, such as xmodmap(1). There's also the imwheel utility, and the evdev input driver for the X Window System.

Although I'm not familiar with the specific configuration, I've found some documentation, such that provides some introductory information about these features of the X Window System. Along with the system manual pages, maybe it could be helpful towards determining a configuration that "Just works"

• MouseCustomizations, at the Ubuntu Wiki
• Mouse buttons, a more in-depth introduction, at the ArchWiki
• Configuring Logitech mice (mx500, etc), Ubuntu Forums

Answer 4

Your mouse wheel scroll mappings match my initial Emacs settings as well.

Add the following to your $HOME/.emacs file.

I find scrolling by four lines optimal.

;; Mouse wheel scroll
;; My scroll wheel is mapped to C-M-( C-M-)
(defun scroll-up-4-lines ()
  "Scroll up 4 lines."
  (interactive)
  (scroll-up 4))

(defun scroll-down-4-lines ()
  "Scroll down 4 lines."
  (interactive)
  (scroll-down 4))

(global-set-key (kbd "C-M-(") 'scroll-down-4-lines)
(global-set-key (kbd "C-M-)") 'scroll-up-4-lines)