Thinkpad 200s, dual screens, setup

Hi I am using a Thinkpad X200s with a Intel Graphic card which supports dual screens. I have installed first Kubuntu 14.04 and then trinity on top of that (I know this approach is not recommended. It would have been better to use the trinity Live CD, but I don't want to reinstall everything). Now I found out about dspdfviewer which allows (for beamer latex generated pdf) to show the transparencies in two screens. I tried that out with my laptop being connected to a external LCD screen, however my laptop screen only was cloned and the dspdfviewer developers told me to try out extended desktop mode. I looked up a bit the trinity kontrol center but could not find anything relevant. So a pointer would be very well come. I would not mind a link to a command tool such as xrand (which was recommended to me as well). Thanks Uwe Brauer