Scrollwheel mice support a middle-button click event when pressing the scrollwheel. This is a great feature, but you may find it irritating. Fortunately it can be disabled.

First, you need to know the id of the mouse, like this:


 $ xinput list | grep 'id='

which prints something like 


 ⎡ Virtual core pointer 	id=2	[master pointer (3)]
 ⎜ Virtual core XTEST pointer 	id=4	[slave pointer (2)]
 ⎜ PixArt Dell MS116 USB Optical Mouse 	id=12	[slave pointer (2)]
 ⎣ Virtual core keyboard 	id=3	[master keyboard (2)]
 Virtual core XTEST keyboard 	id=5	[slave keyboard (3)]
 Power Button 	id=6	[slave keyboard (3)]
 Video Bus 	id=7	[slave keyboard (3)]
 Power Button 	id=8	[slave keyboard (3)]
 Sleep Button 	id=9	[slave keyboard (3)]
 Dell KB216 Wired Keyboard 	id=10	[slave keyboard (3)]
 Dell KB216 Wired Keyboard 	id=11	[slave keyboard (3)]
 Eee PC WMI hotkeys 	id=13	[slave keyboard (3)]

My Dell Usb mouse has printed here for which id=12

so, I can view the my mouse button mapping like:

 $ xinput get-button-map 12

which prints

 1 2 3 4 5 6 7 8 9 10 11 12

here only the first three numbers have meaning for me. They represent the left, middle, and right mouse buttons.

I can turn the middle mouse button off by setting it to 0:


 $ xinput set-button-map 12 1 0 3

Or I can turn the middle-mouse button into a left-mouse button by setting it to 1:


 $ xinput set-button-map 12 1 1 3

> ref. link https://wiki.ubuntu.com/X/Config/Input

it works for me ( kubuntu 18.04 LTS )