When I connect my Surface Pro running 12.04 to a second (non-touch) monitor (Westinghouse Digital Electrons 19'', 1280x1024 for example, but happens with another Dell monitor), the touch screen on my surface responds but places the cursor in the wrong location. If I have the 2nd monitor set to display above my surface, the cursor appears about 1-2 inches directly above where my finder or stylus is touching the screen.
Actually if I touch the screen at the bottom of the Surface screen, the cursor is directly under my finger as expected. The further I move the finger up, the further the cursor moves away from the finger. With my finger at about the midpoint of the surface screen, the cursor is in the black bar, nearly on the second screen. If the second monitor is displayed to the left of the Surface, the cursor is too far to the left, etc.