Not sure what you want to achieve but: Create a non-persistent object in which you store the comment clientside using a nanoflow. Will that help you out?
Hi Matthew,
I would check out the chatter module.
https://appstore.home.mendix.com/link/app/1442/Appronto/Chatter-(FREE)
Matthew,
You may want to check out a webinar being offered by Mendix tomorrow:
https://ww2.mendix.com/Conversational-Platforms.html
Mike
Or maybe the feedback widget is more then enough for your use case?