ok, I understand. So both permission should be accepted. I see two solutions. Either you overwrite the method "check_permission" or you change the method Widget.check_permission in somethink like this:

```python
if instance(self.permission_required, basestring):
  permission_required = [self.permission_required]
else:
  permission_required = self.permission_required
for permission in permission_required:
  if self.request.user.has_perm(permission_required):
    value = True
else:
  value = self.permission_required is None
return value
```