marble mouse middle click fail in 12.04

On recently upgrading to 12.04, I find that the middle click with my logictec marble mouse doesn't work any more (formally achieved by clicking both buttons). Anoying since I can't do a middle-click paste.

Can anyone think of an easy solution? Or should I file a bug?

(theres's already a launchpad question on this, and here's the oldish ubuntu page for configuring a marble mouse.

I found the answer here and here. You need to run the following command:

gsettings set org.gnome.settings-daemon.peripherals.mouse middle-button-enabled true

You only need to do this once - Gnome remebers the setting for your next logon - though you need to do it for each user. If someone knows a way around this, feel free to edit this answer (:

It seems Gnome sets this to 'false' by default, and does so after xorg does it's settings (so it overrides xorg settings in xorg.conf or ...-evdev.conf etc..)

The setting can also be changed with the dconf-editor in the dconf-tools package (thanks Walt). Go to org::gnome::settings-daemon::peripherals::mouse and tick 'middle-button-enabled'.

I am experiencing the same problem after updating from 10.04. I have applied the settings to /usr/share/X11/xorg.conf.d/10-evdev.conf as suggested in https://wiki.archlinux.org/index.php/Logitech_Marble_Mouse and this gives the required scrolling using the trackball, but the two-large-button middle-click merely gives a right-click effect.

I have appended the following settings ing 10-evdev.conf:

Section "InputClass"
        Identifier  "Marble Mouse"
        MatchProduct "Logitech USB Trackball"
        MatchIsPointer "on"
        MatchDevicePath "/dev/input/event*"
        Driver "evdev"
        Option "ButtonMapping" "1 8 3 4 5 6 7 2 2"
        Option "EmulateWheel" "true"
        Option "EmulateWheelButton" "8"
        Option "ZAxisMapping" "4 5"
        Option "XAxisMapping" "6 7"
        Option "Emulate3Buttons" "true"
EndSection

This maps the middle button click to either of the small buttons (8 & 9) and allows the holding down of button 8 (small left button) for the track-ball scrolling. While not ideal (I also prefer the two-large-button==middle-click) this might be a good enough compromise (I think it will be for me at least).

I would also suggest that the loss of Emulate3Buttons is a bug and should be reported. This setting worked fine with this mouse on 10.04.