private void Window_Loaded(object sender, RoutedEventArgs e)
{
    SynchronizationContext ctx = SynchronizationContext.Current;

    ThreadPool.QueueUserWorkItem(_ =>
    {

        WebClient client = new WebClient();

        string html = client.DownloadString("http://www.briankeating.net");
        ctx.Post(state =>
        {
            tbDetails.Text = (string)state;

        }, html);

    });

}

xmlns:valueConverters="clr-namespace:XXX.ValueConverters"
Cursor="{Binding IsBusy, Converter={valueConverters:CursorExtensionConverter}}" 

public class CursorExtensionConverter : MarkupExtension, IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        if (value != null && ((bool)value))
            return Cursors.Wait;           
        else
            return Cursors.Arrow;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        return instance;
    }

    private static CursorExtensionConverter instance = new CursorExtensionConverter();
}

#region Debugging Aides

/// <summary>
/// Warns the developer if this object does not have
/// a public property with the specified name. This
/// method does not exist in a Release build.
/// </summary>
[Conditional("DEBUG")]
[DebuggerStepThrough]
public void VerifyPropertyName(string propertyName)
{
    // Verify that the property name matches a real, 
    // public, instance property on this object.
    if (TypeDescriptor.GetProperties(this)[propertyName] == null)
    {
        string msg = "Invalid property name: " + propertyName;

        if (this.ThrowOnInvalidPropertyName)
            throw new Exception(msg);
        else
            Debug.Fail(msg);
    }
}

/// <summary>
/// Returns whether an exception is thrown, or if a Debug.Fail() is used
/// when an invalid property name is passed to the VerifyPropertyName method.
/// The default value is false, but subclasses used by unit tests might
/// override this property's getter to return true.
/// </summary>
protected virtual bool ThrowOnInvalidPropertyName { get; private set; }

#endregion // Debugging Aides

#region INotifyPropertyChanged Members

/// <summary>
/// Raised when a property on this object has a new value.
/// </summary>
public event PropertyChangedEventHandler PropertyChanged = (s, e) => { };

/// <summary>
/// Raises this object's PropertyChanged event.
/// </summary>
/// <param name="propertyName">The property that has a new value.</param>
protected virtual void OnPropertyChanged(string propertyName)
{
    this.VerifyPropertyName(propertyName);
    this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));           
}

#endregion // INotifyPropertyChanged Members

<Style x:Key="Local_OpenEntityStyle"
           TargetType="{x:Type ListViewItem}">
        <Setter Property="acb:CommandBehavior.Event"
                        Value="MouseDoubleClick" />
        <Setter Property="acb:CommandBehavior.Command"
                        Value="{Binding ElementName=uiEntityListDisplay, Path=DataContext.OpenEntityCommand}" />
        <Setter Property="acb:CommandBehavior.CommandParameter"
                        Value="{Binding}" />
</Style>

Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData)

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="//schemas.microsoft.com/winfx/2006/xaml/presentation">http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525"
        Loaded="OnLoaded"
        >
    <Grid>
        <Border x:Name="bdr">
        <ListView x:Name="lvTest" Initialized="lvInit">
            <ListView.View>
                <GridView>
                    <GridViewColumn Width="140" Header="Column 1" />
                    <GridViewColumn Width="140" Header="Column 2" />
                    <GridViewColumn Width="140" Header="Column 3" />
                </GridView>
            </ListView.View>
        </ListView>
        </Border>
    </Grid>
</Window>
 

using System;
using System.IO;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Markup;

namespace WpfApplication1
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void lvInit(object sender, EventArgs e)
        {
            GridView gv = lvTest.View as GridView;
            gv.Columns.CollectionChanged += (s, gvE) =>
            {
                if (gvE.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Move)
                {
                    SaveState();
                }
            };

        }

        private void SaveState()
        {
            string lvXaml = XamlWriter.Save(lvTest);
            using (var s = new StreamWriter(@"c:\temp\lv.xaml"))
            {
                s.Write(lvXaml);
            }
        }
              
        private void OnLoaded(object sender, RoutedEventArgs e)
        {
            ListView li = null;
            if (File.Exists(@"c:\temp\lv.xaml"))
                bdr.Child = (ListView)XamlReader.Load(File.OpenRead(@"c:\temp\lv.xaml"));           
        }

       
    }
}