<Window x:Class="CheckComboBoxApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:toolkit="clr-namespace:Xceed.Wpf.Toolkit;assembly=Xceed.Wpf.Toolkit"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
 
    <Window.DataContext>
        <XmlDataProvider IsInitialLoadEnabled="True" IsAsynchronous="False">
            <x:XData>
                <Product xmlns="" title="">
                    <Settings title="">
                        <Slot title="" description="">
                            <Item key="01"></Item>
                            <Item key="02"></Item>
                            <Item key="03"></Item>
                            <Item key="04"></Item>
                            <Item key="05"></Item>
                            <Item key="06"></Item>
                            <Item key="07"></Item>
                            <Item key="08"></Item>
                            <Item key="09"></Item>
                        </Slot>
                    </Settings>
                </Product>
            </x:XData>
        </XmlDataProvider>
    </Window.DataContext>
 
    <Grid DataContext="{Binding XPath=Product/Settings/Slot/Item}">
        
        <toolkit:CheckComboBox HorizontalAlignment="Center" 
                               VerticalAlignment="Center" 
                               ItemsSource="{Binding XPath=@key}" />
    </Grid>
</Window>