WPF

<ComboBox IsEditable="True" Text="Language" HorizontalAlignment="Right" VerticalAlignment="Top" Width="95"  Margin="34,21,34,0" ItemsSource="{Binding Languages}" SelectedItem="{Binding SelectedLanguage, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Foreground="#FF434C64" removed="Green" Height="24.96"  />

public void ChangeLanguage()
         {
             if (SelectedLanguage == "en")
             {
                 Thread.CurrentThread.CurrentUICulture = new System.Globalization.CultureInfo("en");

             }
             else
             if (SelectedLanguage == "it-IT")
             {
                 Thread.CurrentThread.CurrentUICulture = new System.Globalization.CultureInfo("it-IT");
             }

         }

public ViewModel()
       {

           LoadData();
           ChangeLanguage();

           Login = new DelegateCommand(this.Logging, delegate()
           {
               return (!String.IsNullOrEmpty(Username) && !String.IsNullOrEmpty(Password) && !String.IsNullOrEmpty(Email));
           });
           Register = new DelegateCommand(this.Registering, delegate()
           {

          return (!String.IsNullOrEmpty(Username) && !String.IsNullOrEmpty(Password) && !String.IsNullOrEmpty(Email));



       });

<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>