Today is the first time I encountered "Please avoid extended discussions in comments. Would you like to automatically move this discussion to chat?", but I had already started typing the text of my comment. Instead of submitting I thought it would be good to follow the advice and start a chat instead of posting another comment. Unfortunately the text I had typed (but not yet submitted) was not copied over to the chat discussion and I lost it because I had not copied the text before hitting the link.
A better behavior for the UI in this case would be to automatically put the unsubmitted comment text into the text box in the discussion window so I could have continued editing it or submitted it. Instead I have to type it all over again. Not a big deal, but this would be a nice little bit of polish that would be helpful for people new to the chat feature.
At very least it should follow the convention on other sites that detect unsaved changes and warn before navigating away that data could be lost.
I would consider this a bug, but I tagged this question as both a
bug and a