Yes, exactly. That's why I said that for this to work, either the cameras os would have to support replacing the built-in lcd by an external one, over usb, or the ML code would have to add this functionality.
The functionality is there, in the camera, because the built-in lcd works. It's internally connected with wiring, so the only question that needs to be answered is wether the source of the input data can be switched from internal wiring, to usb.
So again, my question is, is there such a functionality, either in the os or the ML addon, that supports the receiving over usb of whatever input parameters the built-in lcd normally sends? (and of course sending the output data back also)
I am pretty sure there is, because apps work. They essentially send this data to the camera, along with more complicated data. But I suppose the app is what translates the input to parameters the camera can understand over usb.
For a touchscreen to work, the camera would have to understand the universal "mouse" data the touchscreen sends out. So, again, would the camera be able to interpret this raw, universal code? Could it be as simple as switching on some parameter to "turn on" the input over usb? Or would the camera need extra code?