Touchpad accel, spirals and xset

Richard A. Smith richard at
Mon Jan 18 12:46:36 EST 2010

On 01/18/2010 07:23 AM, Martin Langhoff wrote:

> * Going from xset 7/4 0 to 7/4 1 did not make a noticeable improvement
> -- and does bring the drawback that a fast finger swipe no longer gets
> you across the screen. This is a usability regression, and I don't
> have much evidence to show to counter it.

What you see as a regression I see as an enhancement.  My evidence is 
based on what deployments/pilots talk about when they come give reports 
at 1cc.  When we talk about touchpad problems it often mentioned that 
the children have a hard time positioning the pointer in general due to 
the fine motor control it takes.

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.

Reducing the acceleration also has the benefit that when the jumpyness 
does occur its effect is less because the accel values are less.

> * The new kernel (with modular psmouse, with the new code) stays.
> * xset goes back to 7/4 0

I think that before you make this decision on xset you need to get some 
feedback from deployments or pilots that have users in our target 
demographic.  Children. People like Juliano Bittencourt, the guys in 
Nepal, or Uruguay. I believe Quozl also has access to a small number of 
children testers.

Testing is pretty easy since to test the accel change they don't even 
need the test build.

Richard A. Smith  <richard at>
One Laptop per Child

More information about the Devel mailing list