The 'onKeyDown' callback

Event number: 1
Generated for: Any control which can receive the input focus

A Key Down event is generated when the user presses a key whilst the object has the input focus. The event-specific parameters in ⎕EV are (in index origin 1):

        ⎕EV[6]         Raw ASCII code for this key
        ⎕EV[7]         APL's translated code for this key
        ⎕EV[8]         Scan code (ie key number)
        ⎕EV[9]         Modifiers:
                       (0=unshifted, 1=shifted, 2=alt/option,
                       4=control, 8=command, and sums thereof)