Touchscreen support with multiple screens: pointer location proportional to all screens instead of the touchscreen only

[Yoan]

Touchscreen support seems broken with multiple screens.

* Screen 1: Laptop touchscreen
* Screen 2: HDMI external non-touch screen (at the right of screen 1)

While touchscreen works as expected when no external screen is connected, with both screens there is a touchscreen scaling issue:

Press at the very left of the touchscreen: the pointer matches your finger.
Now swipe slowly to the right: the more you progress, bigger the difference between your finger and the pointer is.
Stop swiping at the very right of the touchscreen: the pointer matches the very right of the non-touch screen.

See the enclosed drawing that illustrates the issue as well as the bug report (added by apport).

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: xorg 1:7.7+19ubuntu14
ProcVersionSignature: Ubuntu 5.4.0-42.46-generic 5.4.44
Uname: Linux 5.4.0-42-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
.proc.driver.nvidia.gpus.0000.01.00.0: Error: [Errno 21] est un dossier: '/proc/driver/nvidia/gpus/0000:01:00.0'
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.suspend: suspend hibernate resume
.proc.driver.nvidia.suspend_depth: default modeset uvm
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86_64 Kernel Module 440.100 Fri May 29 08:45:51 UTC 2020
 GCC version:
ApportVersion: 2.20.11-0ubuntu27.6
Architecture: amd64
BootLog: Error: [Errno 13] Permission non accordée: '/var/log/boot.log'
CasperMD5CheckResult: skip
CompositorRunning: None
CurrentDesktop: MATE
Date: Tue Aug 18 01:12:24 2020
DistUpgraded: Fresh install
DistroCodename: focal
DistroVariant: ubuntu
DkmsStatus:
 virtualbox, 6.1.10, 5.4.0-40-generic, x86_64: installed
 virtualbox, 6.1.10, 5.4.0-42-generic, x86_64: installed
ExtraDebuggingInterest: Yes
GraphicsCard:
 Intel Corporation UHD Graphics 620 (Whiskey Lake) [8086:3ea0] (rev 02) (prog-if 00 [VGA controller])
   Subsystem: Huawei Technologies Co., Ltd. UHD Graphics 620 (Whiskey Lake) [19e5:3e13]
   Subsystem: Huawei Technologies Co., Ltd. GP108BM [GeForce MX250] [19e5:3e13]
InstallationDate: Installed on 2020-05-30 (79 days ago)
InstallationMedia: Ubuntu-MATE 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
MachineType: HUAWEI MACHR-WX9
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-42-generic root=UUID=225d8502-abbf-4298-b1c0-dddd1f895f9c ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/28/2019
dmi.bios.vendor: HUAWEI
dmi.bios.version: 1.19
dmi.board.asset.tag: N/A
dmi.board.name: MACHR-WX9-PCB
dmi.board.vendor: HUAWEI
dmi.board.version: M1080
dmi.chassis.asset.tag: N/A
dmi.chassis.type: 10
dmi.chassis.vendor: HUAWEI
dmi.chassis.version: M1080
dmi.modalias: dmi:bvnHUAWEI:bvr1.19:bd10/28/2019:svnHUAWEI:pnMACHR-WX9:pvrM1080:rvnHUAWEI:rnMACHR-WX9-PCB:rvrM1080:cvnHUAWEI:ct10:cvrM1080:
dmi.product.family: MateBook X
dmi.product.name: MACHR-WX9
dmi.product.sku: C100
dmi.product.version: M1080
dmi.sys.vendor: HUAWEI
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.101-2
version.libgl1-mesa-dri: libgl1-mesa-dri 20.0.8-0ubuntu1~20.04.1
version.libgl1-mesa-glx: libgl1-mesa-glx N/A
version.nvidia-graphics-drivers: nvidia-graphics-drivers-* N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.20.8-2ubuntu2.2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.1.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20200226-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1

[Daniel van Vugt (vanvugt)]

Great bug report, thanks. And sorry for the confusion - I automatically assumed you were using GNOME.