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My Dell XPS 13 (9370) came pre-installed with Ubuntu 16.04. Recently I have been experimenting with Ubuntu 18.04, installed to an external hard-drive.

Whilst using 18.04 I have noticed a fairly frequent issue where the touchpad cursor jumps after certain finger movements. After some experminetation I have managed to work out a technique for reproducing/demonstrating the issue with quite high accuracy.

The technique requires moving a finger on the touchpad fairly slowly, then lifting the finger completely off the touchpad for a seemingly-specific amount of time, then re-engaging the moving finger with the touchpad again but at a different touchpad location.

It's quite hard to describe accurately, so I've also recorded a video, showing both the cursor movement and my finger movement:

https://youtu.be/3y8i0riN_KM

As mentioned, the issue seems to be quite timing-dependant, so as you can see in the video I cannot reproduce it on every attempt. Thankfully I do manage it on my first attempt in the video though; and overall I'd say I have about 60% reproduction success rate.

I have also recorded some libinput-debug-events output when the issue happens:

event16  POINTER_MOTION   +81.50s     2.43/  4.87
event16  POINTER_MOTION   +81.51s     2.43/  4.87
event16  POINTER_MOTION   +81.52s     1.22/  3.65
event16  POINTER_MOTION   +81.52s     2.43/  3.65
event16  POINTER_MOTION   +81.53s     1.22/  2.43
event16  POINTER_MOTION   +81.54s     2.43/  2.43
event16  POINTER_MOTION   +81.54s     2.43/  2.43
event16  POINTER_MOTION   +81.55s     2.43/  2.43
event16  POINTER_MOTION   +81.56s     2.43/  2.43
event16  POINTER_MOTION   +81.56s     1.22/  1.22
event16  POINTER_MOTION   +83.35s   -392.57/-193.26
event16  POINTER_MOTION   +83.36s   -18.14/-12.09
event16  POINTER_MOTION   +83.36s    -3.65/ -2.43
event16  POINTER_MOTION   +83.37s    -3.65/ -2.43
event16  POINTER_MOTION   +83.38s    -2.43/ -1.22
event16  POINTER_MOTION   +83.38s    -2.43/ -1.22
event16  POINTER_MOTION   +83.39s    -2.43/ -1.22
event16  POINTER_MOTION   +83.40s    -2.43/ -1.22
event16  POINTER_MOTION   +83.41s    -2.43/ -1.22
event16  POINTER_MOTION   +83.41s    -1.22/ -1.22
event16  POINTER_MOTION   +83.43s    -1.22/  0.00
event16  POINTER_MOTION   +83.43s    -1.22/  0.00

The erroneous motion is quite obvious from that output, I think, although I not know why it might happen.

(I also noticed the common issue of multiple touchpads being detected by xinput, so I followed the common procedure to tell it to ignore the non-Dell pad; but that has not solved my main issue.)

As mentioned previously, this issue does not occur on the pre-installed Ubuntu 16.04.

Any suggestions on possible fixes for this, or ideas on what part of the system may be causing it, would be much appreciated.

Thanks.

thoughton
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  • You can copy your 16.04 to the external hard drive and then upgrade it rather than a fresh install. There may be enhancements you made in 16.04 that will be respected by 18.04 so the error will go away. Also you would likely be upgrading 16.04 to 18.04 in the future so cloning would be a better test environment anyway. This script can automate the cloning process and give you dual booting features of grub: https://askubuntu.com/questions/1028604/bash-script-to-clone-ubuntu-to-new-partition-for-testing-18-04-lts-upgrade/1028605#1028605 – WinEunuuchs2Unix Jun 24 '18 at 21:10

1 Answers1

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Go to Mouse and Touchpad in Settings. Increase touchpad speed and disable Natural scrolling.

You can install gnome-tweaks.

sudo apt install gnome-tweaks

You can change default behavior. You need to change settings from Keyboard & mouse >> Mouse Click Emulations >> Area

KK Patel
  • 19,083