The same setupEmptyDisabler() code that enables the submit button (e.g. [Reply] turns green) when you enter something in a textarea, should also add mw-ui-destructive to the Cancel button. I.e., the Cancel button should appear red on hover because you'll be losing your entry.

See "Cancel button" discussion on design mailing list.

Version: master
Severity: minor
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=62304