[PATCH] dix: reset last.scroll when resetting the valuator (#45611)

[Chase Douglas]

On 02/10/2012 06:12 PM, Peter Hutterer wrote:
> last.scroll remained on the last-submitted scrolling value but last.valuator
> was changed whenever the slave device changed. The first scrolling delta
> after a switch was then calculated as (last.scroll - new abs value), causing
> erroneous scrolling events.
> 
> Test case:
> - synaptics with a scrolling method enabled, other device with 3+ axes (e.g.
>   wacom)
> - scroll on touchpad
> - use other device
> - scroll on touchpad
> 
> The second scroll caused erroneous button press/release events.
> 
> X.Org Bug 45611 <http://bugs.freedesktop.org/show_bug.cgi?id=45611>
> 
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
> Tested-by: Timo Aaltonen <timo.aaltonen at canonical.com>

Looks right to me.

Reviewed-by: Chase Douglas <chase.douglas at canonical.com>