touch screen thinks other displays are part of touch space

[Vernon Cole]

Running Ubuntu Mate 18.04 on a Dell laptop with a built-in touch screen display, and a second monitor (not touch) on the display port output. The extended monitor is left of the laptop in this case.

 When I touch the left edge of the laptop display, the mouse pointer appears on the extended monitor, not under my finger on the laptop. The "X" value of the mouse seems to be calculated for the entire array of monitors, not the monitor which is actually touch sensitive.

This makes the touch input basically unusable when a second display is in use.

[Victor Kareh (vkareh)]

I was able to solve this by installing `xinput-calibrator` and then running it (called Calibrate Touchscreen from the menu, or xinput_calibrator from the terminal).

You can also try `x11-touchscreen-calibrator`. I think either should work (try both, since it might be hardware-dependent - what laptop do you have?)

[Anthony (anthonyaxenov)]

Confirm the same behaviour on my laptop. I can provide video later if it is necessary.

Resolution of main display is 1366x768
Second monitor stands on the right of laptop, its resolution is 1600x900.
Touchscreen work not for one display, but for the whole desktop. I mean:
1) when I move cursor by finger from left side of main screen to its right side -- cursor moves from left side of main screen to right side of second screen (from 0 to 1366+1600=2966)
2) when I move it from up to down it moves from 0 to 900, not to 768.

`x11-touchscreen-calibrator` works. I installed it (via apt install) and started once from terminal. Touchscreen was fixed immidiately. Output:

$ x11-touchscreen-calibrator
Touchscreen: 'ELAN Touchscreen'
screen: 2966x900, display: 1366x768 (0,43), preferred: 1366x768 (eDP-1), scaling mode: 'Full aspect' RR_Rotate_0
0.460553 0.000000 0.000000
0.000000 0.853333 0.047778
0.000000 0.000000 1.000000

But now I still don't know if I need to make calibrator run on every startup or not.

---

Laptop: Acer Aspire V5-572PG
MATE version: 1.24.0

$ lsb_release -a
LSB Version: core-11.1.0ubuntu2-noarch:printing-11.1.0ubuntu2-noarch:security-11.1.0ubuntu2-noarch
Distributor ID: Ubuntu
Description: Ubuntu 20.04.1 LTS
Release: 20.04
Codename: focal

$ uname -a
Linux Axenov 5.4.0-45-generic #49-Ubuntu SMP Wed Aug 26 13:38:52 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

[Anthony (anthonyaxenov)]

Small addition for those who read my last comment: you need to run `x11-touchscreen-calibrator` only once. After reboot touchscreen will work correctly.

[Martin Wimpress  (flexiondotorg)]

Ubuntu MATE 18.04 is no longer supprted.