Cant disable Item of NSPopUpButton

[Sebastian Reitenbach]

Hi,

I've a NSPopUpButton with some items. Some of them I want just to be disabled.
To do so, I thought I can just get away with:

[[self.popupButton itemWithTitle: @"Item 2"] setEnabled: NO];

but that is not the case.

Is that supposted to work that way, if at all? If so, any hint what I'm doing 
wrong?

Tiny demo app demonstrating just that problem here: 
https://github.com/buzzdeee/TestNSPopUpButton

cheers,
Sebastian