Thank you very much for the detailed reply. It seems that QtCreator scp's the files tarred and tries to untar on the device. After I installed tar everything worked nicely. (Except my MS mouse that malfunctioned and I thought it would fry my Rpi) The question here is does it use X or wayland to display the graphics? Or some other non-standard method (android style)?
Anyway I liked the whole idea very much. Another thing, is that there is an entry in the debian rpi image sources.list that says something about QtonPi. Does that include qtcreator or only qt binaries?
Sorry for the waterfall of questions, I can ask them over at the mailing list if that is better.