I have stripped my full desktop debian 7 x64 to the bare, leaving just xorg and lightdm for a kiosk application.
I have changed the lighdm configuration to auto-login a user. When I boot, this works fine, xorg starts up and without prompt the user is logged in.
However upon login an xterm window starts in the upper left-hand corner of the screen. I have tried in vain to figure out which instance actually started that xterm!
I would of course want to replace it with my kiosk binary wrapped in a watchdog script.