Workbook and worksheet protection fails
*Created originally on Bitbucket by [tristanbrown (Tristan Brown)](https://bitbucket.org/%7Bbbf6fe46-3951-429d-9675-45cc2d3e610b%7D/)*
Tried:
```
#!python
from openpyxl import Workbook
def _create_template(headers):
template = Workbook()
sheet = template.active
sheet.append(headers)
template.security.workbook_Password = 'pw'
sheet.protection.sheet = True
sheet.protection.password = 'pw'
template.save(filename='template.xlsm')
```
When I run this function on a list of column headers and open template.xlsm, all cells are editable without a password. In addition to the above, I tried setting `cell.protection = Protection(locked=True)` for the cells in the sheet, with no further success.
issue