Disabling Enter to Submit Short Answer Responses

I am working on a large project in which about a third of the slides require the user to type in a short answer response and then hit the submit button. There are two important variables attached to them hitting the submit button. 1) Hitting the submit button adds +1 to a ProgressBar variable, which adds a bar to a visible Progress Bar the user sees in the corner. 2) Another attached variable prevents the user from submitting a blank response. 3) The response is submitted (to be graded in conjunction with an LMS).

Of course, as I am editing the completed project, I realize that if the user presses enter instead of the "submit" button on these slides (a very natural thing to do), the slide progresses and none of these triggers are activated. I have tried deactivating the enter button through true/false variables, adding +1 to the ProgressBar if the user presses enter -- nothing works.

Other Articulate users with similar questions have solved this problem by using a text box instead of a quiz slide. For a number of reasons, this doesn't appear to be a viable solution for this project. Is there any other way around this?