pointer (touchpad) aceleration and threshold too low in 11.3.* builds

Eduardo H. Silva hoboprimate at gmail.com
Thu May 17 05:48:10 EDT 2012

2012/5/17 Paul Fox <pgf at laptop.org>:
> eduardo h. silva wrote:
>  > xset q tells that in 11.3.1, the pointer is configured with the values:
>  >
>  > acceleration 7/4 threshold: 1
>  >
>  > This takes 2, 3 and sometimes 4 swipes to move across the screen. It's
>  > quite a difference with a typical touchpad on bigger laptops, and
>  > although the experience can't be duplicated because we can't expect
>  > kids to be already highly trained with a touchpad, I think it could be
>  > improved.
>  >
>  > I think the balance is to have a larger threshold, so that slow
>  > movements are allways acurate, and a higher acceleration, so that
>  > movements across the screen are sufficiently fast (very important in
>  > Sugar to access the frame for example). Managing to drop down the
>  > amount of swipes needed to move across the screen (like 2 swipes)
>  > would be excellent and more in par with the older pre 11.3.* behavior.
> so you think it was better, previously?
> i wonder what has changed.  those xset values were chosen specifically
> to be appropriate for the original ALPS touchpad on XO-1.  it's
> entirely possible, now that we're two laptops and at least as many
> touchpads beyond that, those numbers are incorrect.

I meant to compare between the setting of the builds back in 2008 and
2011 when I began using the XO after a hiatus of years.

I found a discussion started about the change from "acceleration 7/4
threshold: 1" to "acceleration 7/4 threshold: 0)
(http://lists.laptop.org/pipermail/devel/2010-January/027245.html ). A
few messages later, it's shown in xset man page:

"If the `threshold' parameter is provided and 0, the
    `acceleration' parameter will be used in the exponent of a
    more natural and continous formula, giving precise control
    for slow motion but big reach for fast motion, and a
    progresive transition for motions in between.  Recommended
    `acceleration' value in this case is 3/2 to 2, but not
    limited to that range "

Which is exactly what I was looking for. A bit later, Richard A. Smith tells:

"2 of the apps that our deployments spend a lot of time in are scratch
and etoys. Both of these are not completely sugarized apps  and thus
some of the UI elements on the 200 dpi screen are quite small and hard
to use with a fast accel." Though I don't know if he used higher
acceleration values, or with threshold set to 0.

So the thread ends with:

"Find someone with kids and figure out whats the best settings for them."

Next time I am with my nephews I'll be sure to do this, but I already
find threshold 0 a lot better. Perhaps the problem Richard was having
could be solved with a lower acceleration, like 3/2, but still with
threshold 0.


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