I am experimenting with attaching a second monitor to my Ubuntu Natty laptop, and I have noticed an annoying "feature" that makes any multi-monitor setup so unusable that I actually prefer my single-monitor laptop setup.

It appears that the system automatically "scales" the X- and Y-axis sensitivity of the touchpad to match the dimensions of the "virtual" screen that spans across multiple monitors. This is best illustrated with an example. If I set up two monitors side-by-side, the touchpad's X-axis speed is doubled, so that moving my finger the same distance on the touchpad causes the mouse on the screen to move twice as far in the X direction as it did when I had only a single monitor. Yet the Y-axis sensitivity remains unchanged, so all diagonal mouse movements end up at the wrong angle. This makes the touchpad almost completely useless, since the mouse on the screen does not move in the same direction as my hand on the pad.

Is there anything I can do about this? I just want the X- and Y-axis speeds to be identical, and I definitely don't want my mouse sensitivity changing because I added a screen.

The touchpad is a Synaptics touchpad, by the way. The laptop is a Dell M1330 with an nVidia graphics card.

  • I'm seeing the same obnoxious behavior on a Natty desktop with an Apple Magic Trackpad and nVidia graphics. This has been a tricky one to Google for with all the generic "resolution" and "sensitivity" words (but I don't know how to describe our problem otheriwse). I hope somebody finds the answer and posts it here... – rymo Jul 19 '11 at 2:37
  • have the same problem with ubuntu trusty, lenovo Y50 laptop – mathieu Mar 18 '16 at 8:03

Not sure if you're still looking, but I found some info in these two threads: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-input-synaptics/+bug/327428 and bug 591954. Turns out that the dimensions of the touchpad are being scaled to the dimensions of the virtual screen that xorg generates to contain your monitors. Since most people have their monitors side-by-side, you end up with a virtual screen that's probably twice as wide as you'd have with a single monitor, so your horizontal trackpad movements are scaled to be twice as fast. The fix was originally committed almost 2 years ago, which is a bit ridiculous, but...

What I've ended up doing is following the advice of the last post from the first thread and installing the xorg synaptics driver for oneiric from here: http://packages.ubuntu.com/oneiric/amd64/xserver-xorg-input-synaptics/download

This fixed everything up just fine for me.

  • Since Oneiric is released now, and I haven't tested this in a while, I'm just going to mark this as accepted. – Ryan C. Thompson Dec 26 '12 at 18:54
xinput set-prop "SynPS/2 Synaptics TouchPad" "Device Accel Velocity Scaling" 10

(10 is the sensibility , you can tweak it). More info there : https://bbs.archlinux.org/viewtopic.php?pid=963650#p963650

  • What does this setting have to do with the relative sensitivities in the X and Y directions? – Ryan C. Thompson Dec 26 '12 at 18:51

Mouse synchronization problems seem to occur somewhat commonly with many virtualization solutions. So far, the solution that I've found works well in both Xen and VirtualBox is to set the mouse to be emulated as a "tablet device" instead of a regular mouse.

I hope you can find an option like this in your virtualization configuration settings, and thatit resolves your problem.

  • I'm not talking about virtual machines. I'm talking about a multi-monitor setup. Two monitors placed side by side create a "virtual" screen that is double the width of a physical screen. – Ryan C. Thompson Jul 11 '11 at 14:55
  • Oh, that's just an extended screen then. I was thrown off by the word "virtual." – Randolf Richardson Jul 11 '11 at 16:28
  • I believe that the X11 documentation/code refers to it as a virtual screen. – Ryan C. Thompson Jul 11 '11 at 16:41

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