Enable and Disable Tabs
If you want to enable or disable specific tab item(s) you have to use the Boolean property IsEnabled of the class RadTabItem. You can set it from your code-behind, XAML or in Blend.
<telerik:RadTabControl x:Name="radTabControl">
<telerik:RadTabItem Header="Calendar" IsEnabled="False"/>
</telerik:RadTabControl>
RadTabItem newTabItem = new RadTabItem();
newTabItem.Header = "Disabled Item";
// Add the newly created tab item to
// an existing tab control “tabControl”
radTabControl.Items.Add( newTabItem );
// Disable the newly created tab item
newTabItem.IsEnabled = false;
Dim newTabItem As New RadTabItem()
newTabItem.Header = "Disabled Item"
' Add the newly created tab item to'
' some existing tab control “TabControl”'
radTabControl.Items.Add(newTabItem)
' Disable the newly created tab item'
newTabItem.IsEnabled = False