Sao allows to add items on readonly editable trees
Even if the "New" button is disabled, clicking a row and after that press "Enter" key creates a new row.
Steps to reproduce:
- Open an inactive party (with some contact mechanism already added).
- Click the last row of the contact mechanism o2m.
- Press the "Enter" key.
- A new contact mechanism linked to the party is created .
*The same happens for any editable tree regardless of whether the tree is read-only. *Tested in 6.0 and 6.4 series.