15 March 2016
So, funny story... the '?' didnt work on the TI-99/4a in the latest version of TIMXT. It turns out I didn't actually write the code correctly. Go figure... I got the pattern right for the '_', and then fumbled when I replicated it to all of the other keys that you press with a 'shift' but must be sent to the TI as a 'fctn'. In most applications the key worked fine, but I was not actually releasing the shift, and in the TI space, shift-fctn-i is undefined, at best.
Anyway, head on over to the downloads for the latest firmware that fixes that.