Touchpad aspect ratio changes with TwinView

[nstuhrmann]

Binary package hint: xorg

When I attach a second screen to my Thinkpad T61 and activate TwinView using the "Nvidia X Server Settings", the my touchpad becomes more sensitive to horizontal movements and less sensitive to vertical movements.

To demonstrate this, I cut a circular hole in a piece of paper and put it ontop of the touchpad. Using Gimp, I followed the circular boundary using the brush. The result is attached. Without TwinView (black), I almost get a circular shape. However, the aspect ratio for my attempt with TwinView (red) is clearly not 1.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: xorg 1:7.5+5ubuntu1
ProcVersionSignature: Ubuntu 2.6.32-22.36-generic 2.6.32.11+drm33.2
Uname: Linux 2.6.32-22-generic i686
NonfreeKernelModules: nvidia
Architecture: i386
Date: Wed Jun 9 14:44:35 2010
DkmsStatus: nvidia-current, 195.36.15, 2.6.32-22-generic, i686: installed
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release i386 (20100429)
MachineType: LENOVO 766513U
PccardctlIdent:
 Socket 0:
   no product info available
PccardctlStatus:
 Socket 0:
   no card
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-22-generic root=UUID=0c05375c-f9d5-4edb-9b1b-8055d38b82aa ro quiet splash
ProcEnviron:
 PATH=(custom, user)
 LANG=US_en
 SHELL=/bin/bash
SourcePackage: xorg
Symptom: display
dmi.bios.date: 11/14/2008
dmi.bios.vendor: LENOVO
dmi.bios.version: 7LETC5WW (2.25 )
dmi.board.name: 766513U
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr7LETC5WW(2.25):bd11/14/2008:svnLENOVO:pn766513U:pvrThinkPadT61:rvnLENOVO:rn766513U:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 766513U
dmi.product.version: ThinkPad T61
dmi.sys.vendor: LENOVO
glxinfo: Error: [Errno 2] No such file or directory
system:
 distro: Ubuntu
 codename: lucid
 architecture: i686
 kernel: 2.6.32-22-generic

[nstuhrmann (stuhrman)]

I don't observe the problem when I am using a standard USB mouse.

[Luke Gumbley (l-gumbley)]

I have the same issue with a MacBook 13" (synaptics touchpad) running Lucid Lynx. Extremely frustrating! The sensitivity of the trackpad changes if I change the monitor configuration between above/below and side-by-side.

[Gursimran singh (simar)]

Hi bug reporter,
Thank you for taking the time to report this bug and helping to make Ubuntu better.We are sorry that we do not always have the capacity to look at all reported bugs in a timely manner .There have been many changes in ubuntu since that time you reported the bug and your problem may have been fixed with some of the updates.If you could test the current Ubuntu stable release(maverick ubuntu 10.10),this would help us a lot.

[Bryce Harrington (bryce)]

Yep, what's going on here is that the touchpad communicates its dimensions to the xserver, and then xserver compares that to the screen size and scales mouse movement to correspond to the screen. Most of the time that matches expectations, but when the aspect ratio of the screen differs significantly from the aspect ratio of the touchpad, it can produce weird results.

In I've coded a patch to add a way to turn off this behavior, via either an xinput property "Resolution Detect", or an xorg.conf option.

  * Add 116_resolution_detect_option.patch: Provide an option to prevent
    synaptics from communicating the touchpad size to the xserver. This
    can be used to solve problems where differences in touchpad and screen
    dimensions cause the mouse pointer to skip pixels when moving.
    (LP: #327428)

[gpothier (gpothier)]

I'm observing this problem on a Dell Vostro V13 with Oneiric.
The comments of bug #327428 mention that there is an option configurable through xinput that should disable the scaling, but either it doesn't work or I am not using xinput properly:
gpothier@tadzim:adkintun$ xinput --list-props 12 |grep 'Resolution Detect'
 Synaptics Resolution Detect (305): 1
gpothier@tadzim:adkintun$ xinput --set-prop 12 305 0
gpothier@tadzim:adkintun$ xinput --list-props 12 |grep 'Resolution Detect'
 Synaptics Resolution Detect (305): 0

Where device 12 is my touchpad:

gpothier@tadzim:adkintun$ xinput --list |grep Touch
⎜ ↳ SynPS/2 Synaptics TouchPad id=12 [slave pointer (2)]

So it does look like I successfully disabled the option, but I cannot see any change in touchpad behavior (horizontal sensitivity is still about 3 times as much as vertical sensitivity).

[Ahmed Shams (ashams)]

This bug is duplicate of bug #825548

[penalvch (penalvch)]

nstuhrmann, this bug was reported a while ago and there hasn't been any activity in it recently. We were wondering if this is still an issue? If so, could you please test for this with the latest development release of Ubuntu? ISO images are available from http://cdimage.ubuntu.com/daily-live/current/ .

If it remains an issue, could you please run the following command in the development release from a Terminal (Applications->Accessories->Terminal), as it will automatically gather and attach updated debug information to this report:

apport-collect -p xserver-xorg-input-synaptics REPLACE-WITH-BUG-NUMBER

Please note, given that the information from the prior release is already available, doing this on a release prior to the development one would not be helpful.

Thank you for your understanding.

Helpful bug reporting tips:
https://wiki.ubuntu.com/ReportingBugs

[Launchpad Janitor (janitor)]

[Expired for xserver-xorg-input-synaptics (Ubuntu) because there has been no activity for 60 days.]