You need to create a custom selector that will pick up items from your library. After an item has been selected you have to get its ID and check whether it has been tagged.
You could create a custom selector that inherits from Telerik.Libraries.WebControls.Dialogs.ItemSelector.cs
. There you need to override CreateChildControls() and implement a custom view that will be loaded when you are in DisplayMode.ItemsView
. In this custom view you need to bind a repeater to a library item. Inside ItemDataBound event of the repeater you could check whether the item has been tagged or not. If the item is not tagged you can just hide it and it will not appear. Another option is to create an argument for the ID and resolve it later - if the item is not tagged, show an alert.
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items