The 'Add an item' button of one2many editable lists is deactivated
once clicked (since rev. f9a1241) to prevent concurrent record
creation. It is re-activated when the record has been created.
Unfortunately, it might happen that the record is actually not
created, so in this case the button is never re-activated.
This happens for example on the customer invoice form view, if
the user tries to add a line before selecting a partner.
Aaron Bohy
67747e6fa5