touchscreen calibration spans dual screens

[DrPotoroo]

I am testing Ubuntu 14.04 on a microsoft surface pro. Touch and pen input is good out of the box but when a second display is connected the touch and pen inputs are both calibrated to span both screen. I.e., on my setup with external display arranged to be above internal display, both with 1920x1080 resolution, a touch of the top left of the surface pro touch screen triggers a button press at the top left of the external display; whie a touch at the bottom left of the surface pro screen triggers a button press at that location.

What I expected to happen: Touch and pen input could only trigger button presses on the internal, touch display.
What happened: Touch and pen input spans both displays.

lsb_release -rd
Description: Ubuntu Trusty Tahr (development branch)
Release: 14.04