ThreadPool.QueueUserWorkItem

   
  

<Window x:Class="DispatcherExamples.MyWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Use BeginInvoke" Height="300" Width="300"
    >
    <Grid>
      <StackPanel>
        <Button x:Name="useBeginInvokeButton" Content="Use BeginInvoke" />
      </StackPanel>
    </Grid>
</Window>

//File:Window.xaml.cs


using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
using System.Windows.Threading;
using System.Threading;

namespace DispatcherExamples
{
    public partial class MyWindow : System.Windows.Window
    {

        public MyWindow()
        {
            InitializeComponent();

            useBeginInvokeButton.Click += new RoutedEventHandler(useBeginInvokeButton_Click);
        }

        void useBeginInvokeButton_Click(object sender, RoutedEventArgs e)
        {
            ThreadPool.QueueUserWorkItem(delegate
            {
                MyDelegateType methodForUiThread = delegate
                {
                    this.Background = new SolidColorBrush(Color.FromRgb(3,2, 1));
                };
                this.Dispatcher.BeginInvoke(DispatcherPriority.Normal, methodForUiThread);
            });
        }


        public delegate void MyDelegateType();

    }
}