touchpad - Mouse resolution changes when connecting second screen - Ask Ubuntu

issue

my 16.04 laptop has 1366x768 display , perfect. when connect external display (1920x1200) perfect mouse sensitivity (may call resolution or precision).
cursor "jumps" between pixels while moving , found difficult point small areas.
in other words: pointer loose precision.
happen using both mouse or touchpad.

i've seen same issue ("pixel jump") on 16.04 pc mouse , single hi-res display (1920x1080), guess "feature" occurs hi-res displays.

what tried #1

xset -q|grep accel outputs acceleration: 5/1 threshold: 5

hacking around xset parameters found xset -m 1 5 works little better doesn't solve "precision" issue @ (still jumping pixels).

what tried #2

i tried xinput parameter changes while plugging external display: xinput list outputs lot of devices, tested them using: xinput list-props.

the 1 changes when connecting second display is:

xinput list-props "atmel atmel maxtouch digitizer" 

and parameter changes is:

coordinate transformation matrix (144): 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000 

to

coordinate transformation matrix (144): 0.415703, 0.000000, 0.000000, 0.000000, 0.640000, 0.000000, 0.000000, 0.000000, 1.000000 

questions

1. can prevent happen?
2. can modify coordinate transformation matrix parameter xinput?
3. is possible have different pointer behaviour different display resolutions @ same time? mean: "fast" hi-res, "smooth" low-res?

thanx!

i'm answering own question after 2 mounths, approached again issue , found solution.

xinput --list --short outputs 2 drivers related touchpad:

atmel atmel maxtouch digitizer id=11 and
etps/2 elantech touchpad id=14

the 1 changes when connecting external monitor id=11. changing parameters using xinput set-prop 11 144 1 0 0 0 1 0 0 0 1 (144 coordinate transformation matrix prop) didn't change cursor behaviour, tried hacking other driver , succeeded:

xinput set-prop 14 144 .5 0 0 0 .5 0 0 0 1 xinput set-prop 14 273 25 

this way have been able increment cursor precision when moving (through coordinate transformation matrix, prop 144) , keep high acceleration when moving fingers faster on pad (device accel velocity scaling, prop 273).

i think info may useful other full-hd owners too.