I'm running Ubuntu 15.10 using the Cinnamon interface instead of the default. When I run emacs 24.5.1 in an X interface, almost everything works well with the mouse, except the mouse wheel scrolling fails. In the Messages buffer when I try to scroll up, it says:

C-M-( is undefined

And when I scroll down:

C-M-) is undefined

  • Do you really mean Emacs 14 or did you mistype 24?
    – casey
    Nov 4, 2015 at 20:26
  • What is the output of pressing C-h k and then scrolling the mouse up or down? This should describe the key and what it is bound to. e.g. my scroll up is <mouse-4> and runs mwheel-scroll from mwheel.el
    – casey
    Nov 4, 2015 at 20:29
  • Yes, it is emacs 24.5.1, the standard one coming from the Ubuntu repositories.
    – Aphoid
    Nov 4, 2015 at 21:58
  • C-h k gives doesn't describe anything, it just dumps more "C-M-( is undefined" messages in the Messages buffer. Other mouse buttons do display as things in the Help window. <mouse-1>, 2,3 all work. Mouse 6/7 (left right on the scroll wheel) display as "<mouse-6> is undefined" and "<mouse-7> is undefined" respectively.
    – Aphoid
    Nov 4, 2015 at 22:05
  • 1
    Does it do the same thing if you start it as emacs -Q to not load your init file(s)? I've never had to do anything to setup mouse scrolling except in terminal emacs.
    – casey
    Nov 4, 2015 at 22:12

1 Answer 1


I've come up against this same problem on Ubuntu-15.10. It appears that the mwheel.el code isn't being loaded by default.

You can work around this by adding these lines to your ~/.emacs file:

(load "/usr/share/emacs/24.5/lisp/mwheel.elc")
(mouse-wheel-mode t)
  • Didn't help. Not sure what else to try. Tried binding C-M-( and C-M-) to lambda function that scroll up/down with 4 lines -- didn't work as well.
    – dimitarvp
    Apr 13, 2018 at 1:23

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