xaml-sdk/ComboBox/DropDownWithHeaders/Example.xaml

<UserControl x:Class="DropDownWithHeaders.Example"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
             mc:Ignorable="d" 
             DataContext="{StaticResource ViewModel}"
             d:DesignHeight="300" d:DesignWidth="300">    
    <StackPanel>
        <TextBlock Text="This example demonstrates how to display the items in the ComboBox drop down with headers. The approach uses a GridView inside of the Editable and NonEditable Templates." 
                   TextWrapping="Wrap"
                   Margin="10" />
        <StackPanel Margin="10">
            <TextBlock Text="NonEditable ComboBox" />
            <telerik:RadComboBox x:Name="nonEditableCombo" 
                                 MinWidth="300"
                                 HorizontalAlignment="Left"
                                 ItemsSource="{Binding Materials}"
                                 NonEditableTemplate="{StaticResource NonEditableComboBox}" 
                                 DisplayMemberPath="Name" 
                                 VerticalAlignment="Top" 
                                 StaysOpenOnEdit="True" 
                                 SelectedItem="{Binding SelectedMaterial, Mode=TwoWay}"
                                 SelectionChanged="combo_SelectionChanged">
            </telerik:RadComboBox>
        </StackPanel>
        <StackPanel Margin="10">
            <TextBlock Text="Editable ComboBox" />
            <telerik:RadComboBox x:Name="editableCombo"
                                 MinWidth="300"
                                 MaxDropDownHeight="400"
                                 HorizontalAlignment="Left"
                                 ItemsSource="{Binding Materials}"
                                 IsEditable="True" 
                                 EditableTemplate="{StaticResource EditableComboBox}" 
                                 DisplayMemberPath="Name" 
                                 VerticalAlignment="Top" 
                                 StaysOpenOnEdit="True" 
                                 SelectedItem="{Binding SelectedMaterial, Mode=TwoWay}"
                                 SelectionChanged="combo_SelectionChanged">
            </telerik:RadComboBox>
        </StackPanel>
    </StackPanel>
</UserControl>