Thank you smonbrogg, it works!
Here you can find a similar solution by amir and emsee: viewtopic.php?f=4&t=12
There is a general (win7) issue I can't deal with, maybe you can help?
The behavior of the first touch input on WIN 7 is very annoying! A "quick touch" (f.e. pressing several buttons onscreen keyboard) on a button is not possible with the first touch input, you need to leave your finger on the button or move your finger slightly to activate a button (pressed), every following touch input behave normal and makes a quick touch possible. This is annoying because fast simple touch clicks get not recognized if there are no other inputs at the same time... have a look at the attached video. I deactivated Unitys standalone input and touchinput, used Win 7Touch Input (Touchscript) with deactivated mouse input!
Any idea how to get rid of this ?