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Disabled option does not supported properly, can be selected
Need more info.
In my tests everything works fine, just now tried it.
Maybe you're trying to disable it just by adding the attribute "disabled" to the original select? If so, then you should use the API method instead.
Try the "disable" feature here using the provided button and see if it works there.
I mean possibility for disable an option not whole select
Oh, I've read it wrong.
Honestly, I've never seen disabled option in use anywhere, so I thought that it's not needed :)
I'll add the support for this in the next release.
In the 0.8 release added the support for disabling options and optgroups.