or
<telerik:RadComboBox Name="comboWorkingPlan" Height="20" Width="100"DisplayMemberPath="Name"SelectionChanged="comboWorkingPlan_SelectionChanged"SelectedItem="{Binding Source={StaticResource MainUIDataSource}, Path=Class, Mode=TwoWay}"ItemsSource="{Binding Source={StaticResource MainUIDataSource}, Path=PlansDataSource.AllClasses}" Initialized="comboWorkingPlan_Initialized"/>