synaptics bug 31636: non-uniform horizontal and vertical acceleration

[Peter Hutterer]

On Tue, Apr 03, 2012 at 09:29:37AM -0700, Chase Douglas wrote:
> On 04/02/2012 08:28 PM, Martin Spacek wrote:
> > Hello,
> > 
> > About a year ago, Chase Douglas suggested I post about this here. I've only 
> > recently become annoyed enough to finally do so.
> > 
> > When I add a secondary monitor horizontally to my primary one, my synaptics 
> > touchpad (on a Thinkpad W510) becomes much more sensitive horizontally than 
> > vertically. If I add the secondary monitor vertically, it becomes more sensitive 
> > vertically than horizontally. Others have reported the same issue on different 
> > machines. Here are the relevant bug reports:
> > 
> > https://bugs.freedesktop.org/show_bug.cgi?id=31636
> > 
> > https://bugs.launchpad.net/xorg-driver-synaptics/+bug/726832
> > 
> > Surely this can't be a design feature, can it? No other input devices (external 
> > mouse or trackpoint, both via evdev apparently) behave this way, and neither 
> > does the touchpad in Windows. This essentially breaks the touchpad for me on a 
> > multi-monitor setup. Fortunately, when plugged into an external monitor, there's 
> > usually access to an external mouse, which is perhaps why this one has flown 
> > under the radar for so long. This bug has been around for coming up to a year 
> > and a half. Could someone maybe have a look at it?
> 
> I have heard from a few people that they actually prefer this behavior.
> I think we either need to stick with what we have or make it
> configurable (and maybe change the default).
> 
> Peter, any thoughts?

no, it's a bug. the speed shouldn't change when you plug a screen in. not
sure yet what exactly causes it, but it's somewhere in the server, the
acceleration the driver applies.

Cheers,
  Peter