A Boolean value that indicates whether the preference pane is able to be deselected.
- macOS 10.1+
The possible values are described in Help Menu Support. The default implementation always returns
NSPreference. Override this method if your pane needs to cancel or delay a deselect action. If you override this method to return
NSPreference, you must invoke
reply(to when you have determined whether or not the deselection can occur.