Steps to replicate:
- Open the New Discussion Tool.
- Enter some text in the tool's Description field.
- Click the Add Topic button.
- At this point you will get the feedback message "Please provide a topic for your comment. If you click "Add topic" again, your comment will be added without a topic."
- Type something into the Topic field.
I feel at this point the feedback message should disappear, although I am not sure if it's possible to repaint the page at this point.