Every now and again I will accidentally click the middle mouse button when I go to grab my mouse, and KDE will dump my clipboard buffer into a BASH shell. Not good. Could run something damaging if I’m unlucky. So see here for the solution. Basically run this to get the mouse device ID:

xinput list | grep 'id='

Then to edit e.g. device 10 to disable middle mouse button:

xinput set-button-map 10 1 0 3

To persist the changes add the set-button-map command to e.g. ~/.xstartup.

Or you can add a pointer configuration to ~/.Xmodmap like this:

pointer = 1 0 3 4 5 6 7 8 9 10

And make sure xmodmap is applied at start-up with an autostart file like e.g. ~/.config/autostart/mouse-config.desktop:

[Desktop Entry]
Type=Application
Name=mouse-config
Comment=Disables middle mouse button.
Exec=xmodmap /home/jj5/.Xmodmap