This doesn't just happen when submitting a comment to the main post, but also replying in a thread, if that matters/gets handled differently.
I know ;)
It's just missing some little code once the submission is confirmed.
qelem.parentNode.querySelector('.cmpreview').style.display = 'none';
That's what I figured; some quick onclick="DoTheSameThingAsWhenIClickTheXButton()". or something like that.
It's already fixed on Poal's test instance.
Will push it later.
(post is archived)