Hi lcava1.
I wanted to let you know that Blair has been working on your problem and created a patch for MediaLab version 2012 that includes a feature to disable the cancel button. By typing <specify!> in the text label field of a response option, this will disable the cancel the button until something is typed in the box of the window that appears. The box appears the same as if you used <specify>; it's just now that the cancel button will not allow participants to bypass typing something in the box.
All you need to do is go the download section of the Empirisoft website and click on the link that says "Download MediaLab v2012.4.130 now!" This will simply update any copy of MediaLab v2012 to enable the <specify!> feature.
As always, please don't hesitate to contact me if you have any questions about this new feature or any other features of MediaLab.
Jason Reed
Empirisoft Software Support Specialist