Thanks for the information.
We will fix this in a future release. As a workaround you can use SelectedIndexChanging event and cancel it if user tries to select the Disabled item. Please excuse us for the inconvenience.
A bit off topic: please ask the purchase holder to add you as a License Developer to the purchase. This will give you full access to the products your company has purchased, to our downloads section, and to our support ticketing system. Additionally, all your questions will be reviewed according to the license you have. More information on License Developers you can find here: www.telerik.com/account/faqs.aspx.
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