WPF

<TreeView>
    <TreeViewItem Header="Category" ItemsSource="{Binding Categories}" />
    <TreeViewItem Header="Colors" ItemsSource="{Binding Colors}" />
</TreeView>

<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:local="clr-namespace:test"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
x:Class="MainWindow" Title="main" Height="600" Width="800">
<Grid></Grid>
</Window>

Imports System.IO
Class MainWindow
    Public Shared ThemeTempFolder As String = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) & "\Theme\"
    Public Shared themeGrid As Grid
    Private Sub Window_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
        Debug.Print(ThemeTempFolder)
        loadInterface()
    End Sub
    Sub loadInterface()
        ' Load extracted (grid) xaml file as content of the window
        Dim GridUri As String = ThemeTempFolder & "theme.xaml"
        Dim fs As FileStream = New FileStream(GridUri, FileMode.Open, FileAccess.Read)
        Dim sri = TryCast(System.Windows.Markup.XamlReader.Load(fs), Grid)
        Me.Content = sri
        fs.Close()
        ' Liens, dans le code, aux ?l?ments de l'interface charg?e en Xaml.
        themeGrid = LogicalTreeHelper.FindLogicalNode(sri, "themeGrid")
    End Sub
End Class
Public Class imgurlConvert
    Implements IValueConverter
    Public Function Convert(ByVal value As Object, ByVal targetType As Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements IValueConverter.Convert
        Dim valConv As String = MainWindow.ThemeTempFolder & value
        If File.Exists(valConv) Then
            Return valConv
        End If
        Return Nothing
    End Function
    Public Function ConvertBack(ByVal value As Object, ByVal targetType As Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements IValueConverter.ConvertBack
        Return value
    End Function
End Class

<Grid xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:local="clr-namespace:WpfApplication1" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:System="clr-namespace:System;assembly=mscorlib" Name="themeGrid">
    <Grid.Resources>
        <local:imgurlConvert x:Key="urlConvert" />
    </Grid.Resources>
    <Grid Name="mainGrid">
        <Image Source={Binding Path="image.png", Converter={StaticResource urlConvert}} CacheOption="OnLoad" x:Name="Image1"/>
    </Grid>
</Grid>

<Style x:Key="ValidationTextBoxStyle" TargetType="{x:Type TextBox}" BasedOn="{StaticResource {x:Type TextBox}}">
<Setter Property="Validation.ErrorTemplate"
	Value="{StaticResource ErrorTemplate}" />
	<Style.Triggers>
	<Trigger Property="Validation.HasError" Value="True">
	<Setter Property="ToolTip">
	<Setter.Value>
	<Binding Path="(Validation.Errors)[0].ErrorContent" RelativeSource="{x:Static RelativeSource.Self}" />
							</Setter.Value>
	</Setter>
	<Setter Property="BorderBrush" Value="#FF666666"/>
   </Trigger>
 </Style.Triggers>
</Style>
 
<TextBox x:Name="FileObjectName" Grid.Column="1" VerticalContentAlignment="Center" Height="Auto" MaxLines="1"
                   Style="{StaticResource ValidationTextBoxStyle}" IsEnabled="{Binding IsNameEditable}">
<TextBox.Text>
<Binding Path="Name" Mode="TwoWay" UpdateSourceTrigger="PropertyChanged" ValidatesOnDataErrors="True" ValidatesOnExceptions="True">
						<Binding.ValidationRules>
							<validation:LibraryObjectFileNameValidationRule
								ValidatesOnTargetUpdated="True"
								PropertyName="{x:Static resources:CommonStorageUIContent.FileNamePropertyName}" />
							<validation:PropertyLengthValidationRule 
								ValidatesOnTargetUpdated="True"
								IsAlphaNumericValuesOnly="True"
								MaxPropertyLength="{x:Static validation:Constants.KeyPropertyMaxLengthDefaultValue}"
								PropertyName="{x:Static resources:CommonStorageUIContent.FileNamePropertyName}"/>
						</Binding.ValidationRules>
					</Binding>
				</TextBox.Text>
			</TextBox>

<Style TargetType="telerik:GridViewRow">
    <Setter Property="IsSelected" Value="{Binding IsExpanded, RelativeSource={RelativeSource Self}}" />
</Style>

<Style TargetType="telerik:GridViewRow">
    <Setter Property="IsExpanded" Value="[WHAT GOES HERE?]" />
</Style>

<ComboBox x:Name="CategoryCombo"
            Grid.Row="1"
            ItemsSource="{Binding Categories}"
            SelectedValuePath="Id"
            DisplayMemberPath="Category"
            VerticalAlignment="Center"
            Height="24"
            Width="375"/>

<views:LookupComboControl Grid.Row="2"
                            CategoryId="{Binding ElementName=CategoryCombo, Path=SelectedValue, Mode=TwoWay}"
                            Height="70"
                            Width="400"/>

public class LookupComboControlViewModel : _ModelBase
{
    private List<PersonModel> _People = new List<PersonModel>();
    public List<PersonModel> People
    {
        get { return _People; }
        set
        {
            if (_People != value)
            {
                _People = value;
                RaisePropertyChanged("ComboSourceData");
            }
        }
    }

    private string _CategoryName;
    public string CategoryName
    {
        get { return _CategoryName; }
        set
        {
            if (_CategoryName != value)
            {
                _CategoryName = value;
                RaisePropertyChanged("CategoryName");
            }
        }
    }

    private int _CategoryId;
    public int CategoryId
    {
        get { return _CategoryId; }
        set
        {
            if (_CategoryId != value)
            {
                _CategoryId = value;
                RaisePropertyChanged("CategoryId");

                loadData();
            }
        }
    }

    private void loadData()
    {
        DAL dal = new DAL();

        People = dal.GetPeopleForCategory(CategoryId);
    }
}

public LookupComboControl()
{
    InitializeComponent();

    this.DataContext = new LookupComboControlViewModel();
}

public int CategoryId
{
    get { return (int)GetValue(CategoryIdProperty); }
    set { SetValue(CategoryIdProperty, value); }
}

public static readonly DependencyProperty CategoryIdProperty =
    DependencyProperty.Register("CategoryId", typeof(int), typeof(LookupComboControl));