[RFC] libinput configuration interface

Alexander E. Patrakov patrakov at gmail.com
Wed Feb 19 06:55:28 CET 2014

19.02.2014 04:52, Peter Hutterer wrote:
> The set of touchpad patches I sent out recently already handle this by
> default. When the physical clickpad button is depressed, the driver picks
> the finger that is pressing the button (sometimes guessing, but hey...).
> That finger cannot control the pointer movement until the button is released
> again.
> In your specific use case, the driver would see two touchpoints and it will
> select the one closer to the bottom edge as the pressing finger (i.e. your
> thumb). The index finger can still move while the button is down.

 From my experience with the Sony touchpad (Vaio Z23A4R laptop), I'd say 
that it doesn't solve the whole problem. Here is what goes wrong with 
the old synaptics driver by default and can be worked around with 

         Option "SoftButtonAreas" "4360 0 4000 0 2880 4359 3500 0"
         Option "AreaBottomEdge" "3500"

1. I move the right-hand index finger on the touchpad, thus moving the 
pointer to the place where I want to click.

2. I place the left-hand index finger into the virtual-button area, 
while still keeping the right finger on the touchpad. I cannot remove 
the right-hand finger: if I do that, while the contact area shrinks, its 
center also moves, and the driver picks that up.

3. As I increase the pressure on the left-hand finger until the touchpad 
clicks, the contact area increases. Unfortunately, its center moves, 
too, and this can accumulate to ~2-3 pixels until it clicks.

The important point is that the bad thing happens before the hardware 
button click, so the quoted solution totally misses the point.

So we need something, either a sledgehammer solution in the form of 
ignoring all motion in the virtual button area (but that would break 
Sony Vaio Duo 13 because the only usable height of the virtual button 
area is 100% there), or some very good filter that pays attention to 
changes in pressure and filters any spurious movement (i.e. any movement 
that is combined with significant pressure changes) out.

But hey, Sony in their new laptops started to ignore the problem under 
Windows, too, so I think I just have to swallow this and/or use my 
Bluetooth mouse.

Alexander E. Patrakov

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