Add the possibility to have disabled (non selectable) items

[opncow]

It would be nice to be able to have disabled (non selectable) items in the ChosenListBox.

[jDramaix]

Disabled option are simply hidden

[jDramaix]

I wouldn't close this issue. I think it is valid. For the time being the disabled items are hidden (and even removed) but we should give the ability to the developer to show them. The disabled options should have a specific css class name in order to differentiate them visually and they shouldn't be selectable.

Chosen has implemented this behavior: http://harvesthq.github.io/chosen/#selected-and-disabled-support