Found on Firefox 33.0.3, on Platform UI interface.
The tag field that is common for folders and galleries for instance usually has a message "This field is empty" when such field is empty.
It appears though this message doesn't appear on contents of these types created after the ezpublish installation, even though the default folders on an ezpublish installation show the message correctly.
Articles on the other end seem to show the message on platformUI interface, even if created after installation.