In reply to:

An useful project would be an external satellite display with display and buttons.
I don't know foxtrot_xray project very well.
Is it possible to expand this project and integrate some buttons?



Don't think he in particular was interested in that, but that's what I've done; A Grayhill joystick + optical encoder in one axis takes care of all 7 empeg face actions, and then I added 6 extra buttons to be assigned in software to whatever... a BasicStamp (yeah, I know, but it was easier) takes the input and sends a character down the serial for each button press/release. I mounted the joystick where the cig lighter was in my car (and hacked the lighter itself into a knob), and replaced the passenger airbag disable panel with those 6 buttons and garage/gate/power/etc buttons. See my posts here, here, here, and various other places for more info.