How do I turn off bullets in NSSecureTextField?

I have a password dialog that uses NSSecureTextField and I want to include a "Show password" checkbox so I can show the password being typed in clear 开发者_开发问答text.

Copying works for the case of going from the secure field to the unsecure field, but going from the unsecure field to the secure field doesn't work: setStringValue: seems to have no effect on the secure field.

Create an NSTextField in the same location with the same properties. When the checkbox is checked, change focus, copy current value, and hide and show the appropriate text field. The obvious 'setBulleted:' method does not exist.