I purchased a new trackball (Logitech MX Ergo) which is superbly supported by 'Solaar' software.
Solaar is a pretty good (albeit slow starting) driver+config-app for Logitech mice.
One thing is missing though: You can not disable acceleration (which is a bit problematic with a trackball, especially when gaming)
And since solaar runs the mouse, mate-mouseconfig is ignored.
So what to do ?
I first used the command 'xinput' to find out the exact name of my pointing device:
thom@monolith:~$ xinput ⎡ Virtual core pointer id=2 [master pointer (3)] ⎜ ↳ Virtual core XTEST pointer id=4 [slave pointer (2)] ⎜ ↳ Logitech MX Ergo id=8 [slave pointer (2)] ⎜ ↳ Corsair Corsair Gaming K55 RGB Keyboard id=9 [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)] ↳ Power Button id=7 [slave keyboard (3)] ↳ Logitech MX Ergo id=10 [slave keyboard (3)] ↳ Corsair Corsair Gaming K55 RGB Keyboard id=11 [slave keyboard (3)]
Then I searched for the name of the parameter to disable acceleration
thom@monolith:~$ xinput list-props "pointer:Logitech MX Ergo" |grep -i accel libinput Accel Speed (302): 0.000000 libinput Accel Speed Default (303): 0.000000 libinput Accel Profiles Available (304): 1, 1 libinput Accel Profile Enabled (305): 0, 1 libinput Accel Profile Enabled Default (306): 1, 0
According to the libinput documentation:
libinput Accel Profile Enabled
3 boolean values (8 bit, 0 or 1), in order "adaptive", "flat", "custom". Indicates which acceleration profile is currently enabled on this device.
It is a bit cryptic how they wrote it but I understood it as:
0 0 = adaptive
0 1 = flat
1 0 = custom
Then I added this line to my "$HOME/.profile" :
xinput set-prop "pointer:Logitech MX Ergo" "libinput Accel Profile Enabled" 0 1
Which, indeed switched off acceleration a.k.a. a 'flat' profile.
This will work for other pointing devices too (tested with my old Logitech M570).
Just don't forget to adjust the commands to the name of your pointing device.