Submitting the form on Enter in the current UI goes against all expectations.
It is hardcoded in the javascript to override the default behavior (browsers are actually quite sane in this case and know not to auto-submit from a textarea because that's bad).
Either make it not a text area or make it not submit on Enter.
Version: unspecified
Severity: normal
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=52133