If you invoke the <span class="code">GetData</span> method, ...

<span class="foo">hello</span>

<span class="bar">hello</span>

<span class="foo"><span class="bar">world</span></span>

        

public static class WinApi
{
  /// <summary>
  /// Gives focus to a given window.
  /// </summary>
  [DllImport("USER32.DLL")]
  public static extern bool SetForegroundWindow(IntPtr hWnd);

  public static void ActivatePopup(Popup popup)
  {
    //try to get a handle on the popup itself (via its child)
    HwndSource source = (HwndSource)PresentationSource.FromVisual(popup.Child);
    IntPtr handle = source.Handle;

    //activate the popup
    SetForegroundWindow(handle);
  }
}

<Window x:Class="WpfApplication2.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="150" Width="150">
    <StackPanel VerticalAlignment="Center">
      <Image Source="/Images/Add-Item.png" Stretch="None" />
      <Image Source="/Images/Remove-Item.png" Stretch="None"/>
    </StackPanel>
</Window>

<Window x:Class="WpfApplication2.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="150" Width="150">
    <StackPanel VerticalAlignment="Center">
      <Image Source="/Images/Add-Item.png" Stretch="None" />
      <Image Source="/remove-item.png" Stretch="None"/>
    </StackPanel>
</Window>

//get all TextBox controls within the grid:
Grid container;
IEnumerable<TextBox> editors = container.FindChildren<TextBox>();

//start a the root (the window itself)
Window window = this;
foreach (Image img in window.FindChildren<Image>())
{
  Console.WriteLine("Image source: " + img.Source);
}

//only examine the contents of the editor
RichTextBox editor = this.txtContent;
foreach (Image img in editor.FindChildren<Image>())
{
  Console.WriteLine("Image source: " + img.Source);
}

/// <summary>
/// Analyzes both visual and logical tree in order to find all elements
/// of a given type that are descendants of the <paramref name="source"/>
/// item.
/// </summary>
/// <typeparam name="T">The type of the queried items.</typeparam>
/// <param name="source">The root element that marks the source of the
/// search. If the source is already of the requested type, it will not
/// be included in the result.</param>
/// <returns>All descendants of <paramref name="source"/> that match the
/// requested type.</returns>
public static IEnumerable<T> FindChildren<T>(this DependencyObject source)
                                             where T : DependencyObject
{
  if (source != null)
  {
    var childs = GetChildObjects(source);
    foreach (DependencyObject child in childs)
    {
      //analyze if children match the requested type
      if (child != null && child is T)
      {
        yield return (T) child;
      }

      //recurse tree
      foreach (T descendant in FindChildren<T>(child))
      {
        yield return descendant;
      }
    }
  }
}

/// <summary>
/// This method is an alternative to WPF's
/// <see cref="VisualTreeHelper.GetChild"/> method, which also
/// supports content elements. Do note, that for content elements,
/// this method falls back to the logical tree of the element.
/// </summary>
/// <param name="parent">The item to be processed.</param>
/// <returns>The submitted item's child elements, if available.</returns>
public static IEnumerable<DependencyObject> GetChildObjects(
                                            this DependencyObject parent)
{
  if (parent == null) yield break;
  

  if (parent is ContentElement || parent is FrameworkElement)
  {
    //use the logical tree for content / framework elements
    foreach (object obj in LogicalTreeHelper.GetChildren(parent))
    {
      var depObj = obj as DependencyObject;
      if (depObj != null) yield return (DependencyObject) obj;
    }
  }
  else
  {
    //use the visual tree per default
    int count = VisualTreeHelper.GetChildrenCount(parent);
    for (int i = 0; i < count; i++)
    {
      yield return VisualTreeHelper.GetChild(parent, i);
    }
  }
}

<Grid Background="Green">
  <Path Stretch="Fill" Stroke="#5A000000" Margin="25,62,0,0"
        Width="1" Height="100" Data="M130,176 L130,303.03543"/>
  <Path Stretch="Fill" Stroke="#5AFFFFFF" Margin="26,62,0,0"
        Width="1" Height="100" Data="M130,176 L130,303.03543"/>
</Grid>

<Grid x:Name="uncheckedState">
  <Border BorderBrush="#49FFFFFF" BorderThickness="1,1,0,0"/>
  <Border BorderBrush="#49000000" BorderThickness="0,0,1,1"/>
</Grid>

<Grid x:Name="checkedState" Visibility="Collapsed">
  <Border BorderBrush="#49000000" BorderThickness="1,1,0,0"/>
  <Border BorderBrush="#49FFFFFF" BorderThickness="0,0,1,1"/>
</Grid>  

<Style TargetType="{x:Type ToggleButton}">
  <Setter Property="Template">
    <Setter.Value>
      <ControlTemplate TargetType="{x:Type ToggleButton}">
        <Grid x:Name="mainGrid" Margin="0,0,1,1">

          <Grid x:Name="uncheckedState">
            <Border BorderBrush="#49FFFFFF" BorderThickness="1,1,0,0"/>
            <Border BorderBrush="#49000000" BorderThickness="0,0,1,1"/>
          </Grid>

          <Grid x:Name="checkedState" Visibility="Collapsed">
            <Border BorderBrush="#49000000" BorderThickness="1,1,0,0"/>
            <Border BorderBrush="#49FFFFFF" BorderThickness="0,0,1,1"/>
          </Grid>   

          <!--
            WPF needs a background to toggle IsChecked
            if the ContentPresenter does not fill the whole area
          -->
          <Border Background="#00000000" />

          <ContentPresenter VerticalAlignment="Center"
                            HorizontalAlignment="Center" />

        </Grid>

        <!-- triggers toggle visual appearance -->
        <ControlTemplate.Triggers>
          <Trigger Property="IsChecked" Value="True">
            <Setter TargetName="checkedState"
                    Property="Visibility"
                    Value="Visible" />
            <Setter TargetName="uncheckedState"
                    Property="Visibility"
                    Value="Collapsed" />
            <Setter TargetName="mainGrid"
                    Property="Margin"
                    Value="1,1,0,0"/>
          </Trigger>
        </ControlTemplate.Triggers>
      </ControlTemplate>
    </Setter.Value>
  </Setter>
</Style>

<ToggleButton Width="100" Height="24" Content="hello world" />

/// <summary>///
 Hosts the <see cref="AlarmEvent"/> attached routed event.
/// </summary>
public static class Monitor{

  /// <summary>
  /// Alarm Attached Routed Event
  /// </summary>
  public static readonly RoutedEvent AlarmEvent =
      EventManager.RegisterRoutedEvent("Alarm",
                                       RoutingStrategy.Bubble,
                                       typeof (RoutedEventHandler),
                                       typeof (Monitor));
}

/// <summary>
/// A static helper method to raise the Alarm event on a target element.
/// </summary>
/// <param name="target">UIElement or ContentElement on which to raise
/// the event</param>
internal static RoutedEventArgs RaiseAlarmEvent(DependencyObject target)
{
  if (target == null) return null;

  RoutedEventArgs args = new RoutedEventArgs();
  args.RoutedEvent = AlarmEvent;

  if (target is UIElement)
  {
    (target as UIElement).RaiseEvent(args);
  }
  else if (target is ContentElement)
  {
    (target as ContentElement).RaiseEvent(args);
  }

  return args;
}

private void btnTrigger_Click(object sender, RoutedEventArgs e)
{
  //raise the attached event on the status control
  Monitor.RaiseAlarmEvent(status);
}

<UserControl.Triggers>
  <EventTrigger RoutedEvent="FrameworkElement.Loaded">
    <BeginStoryboard Storyboard="{StaticResource ShowWarning}"/>
  </EventTrigger>
</UserControl.Triggers>

<UserControl.Triggers>
  <EventTrigger RoutedEvent="att:Monitor.Alarm">
    <BeginStoryboard Storyboard="{StaticResource ShowWarning}"/>
  </EventTrigger>
</UserControl.Triggers>

<UserControl
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:att="clr-namespace:AttachedEventSample"
  ...  >

<Window.Resources>

  <cmd:HelloWorldCommand x:Key="SayHello" />

</Window.Resources>

<Button Command="{StaticResource SayHello}" />

<Button Command="{cmd:HelloWorldCommand}" />

/// <summary>
/// Basic implementation of the <see cref="ICommand"/>
/// interface, which is also accessible as a markup
/// extension.
/// </summary>
public abstract class CommandExtension<T> : MarkupExtension, ICommand
    where T:class, ICommand, new()
{
  /// <summary>
  /// A singleton instance.
  /// </summary>
  private static T command;

  /// <summary>
  /// Gets a shared command instance.
  /// </summary>
  public override object ProvideValue(IServiceProvider serviceProvider)
  {
    if (command == null) command = new T();
    return command;
  }

  /// <summary>
  /// Fires when changes occur that affect whether
  /// or not the command should execute.
  /// </summary>
  public event EventHandler CanExecuteChanged
  {
    add { CommandManager.RequerySuggested += value; }
    remove { CommandManager.RequerySuggested -= value; }
  }

  /// <summary>
  /// Defines the method to be called when the command is invoked.
  /// </summary>
  /// <param name="parameter">Data used by the command.
  /// If the command does not require data to be passed,
  /// this object can be set to null.
  /// </param>
  public abstract void Execute(object parameter);

  /// <summary>
  /// Defines the method that determines whether the command
  /// can execute in its current state.
  /// </summary>
  /// <returns>
  /// This default implementation always returns true.
  /// </returns>
  /// <param name="parameter">Data used by the command.  
  /// If the command does not require data to be passed,
  /// this object can be set to null.
  /// </param>
  public virtual bool CanExecute(object parameter)
  {
    return true;
  }
}

public class HelloWorldCommand : CommandExtension<HelloWorldCommand>
{
  public override void Execute(object parameter)
  {
    MessageBox.Show("Hello world.");
  }
}

//ILogger is the facade. Behind the scenes,
//a framework of your choice is used
ILogger logger = LoggerService.Logger;
logger.Log("hello world");

//create a new logger instance
string file = @"C:\logfile.txt";
ILogger logger = BitFactoryLogger.CreateSingleFileLogger(file);

//use the global LoggerService to store the logger
LoggerService.SetLogger(logger);

...

//this will store the info in the log file
LoggerService.Logger.Log("This is an information");

public void LogData(ILogger logger)
{
  logger.Log("An information");
  logger.Log("Something Happened", TraceEventType.Warning);

  //LogItem is the most verbose version
  LogItem item = new LogItem();
  item.Message = "My Message";
  item.EventId = 999;
  item.Categories.Add("Foo");
  item.Priority = 10;
  logger.Log(item); 

  try
  {
    DivideByZero();
  }
  catch(Exception e)
  {
    logger.Log(e);
    logger.Log("Additional message.", e);
    logger.Log("Additional message.", e, TraceEventType.Critical);
  }
}

//init IOC container builder
var builder = new ContainerBuilder();

//register single logger instance
ILogger logger;

#if (DEBUG)
  logger = new ConsoleLogger();
#else
  logger = BitFactoryLogger.CreateSingleFileLogger(AppUtil.LogFile);
#endif

//register logger
builder.Register(logger).As<ILogger>();

public void InitApp()
{
  //create a file logger (use BitFactory facade)
  string logFile = @"C:\MyLogFile.txt";
  ILogger logger = BitFactoryLogger.CreateSingleFileLogger(logFile);

  //register as globally used logger
  LoggerService.SetLogger(logger);
}

private void Foo()
{
  try
  {
    DoSomethingWrong();
  }
  catch(Exception e)
  {
    //get registered logger and log exception
    ILogger logger = LoggerService.Logger;
    logger.Log(e);
  }
}

namespace Hardcodet.Util.Logging
{
  /// <summary>
  /// Provides a global repository for a given <see cref="ILogger"/>
  /// instance. This class ensures that the <see cref="Logger"/>
  /// property is never nullo - in case no logger is defined, it
  /// automatically installs a <see cref="NullLogger"/>
  /// instance.
  /// </summary>
  public static class LoggerService
  {
    private static ILogger logger = new NullLogger();

    /// <summary>
    /// Gets the installed <see cref="ILogger"/> implementation.
    /// </summary>
    /// <remarks>This property always returns a valid
    /// logger.</remarks>
    public static ILogger Logger
    {
      get { return logger; }
    }

    /// <summary>
    /// Installs a given logger or resets the <see cref="Logger"/>
    /// to a <see cref="NullLogger"/> instance if the
    /// <paramref name="loggerImplementation"/> is a null
    /// reference.
    /// </summary>
    /// <param name="loggerImplementation">The logger to be
    /// used globally, or a null reference in order to reset
    /// the service.</param>
    public static void SetLogger(ILogger loggerImplementation)
    {
      logger = loggerImplementation ?? new NullLogger();
    }
  }
}

using System;

namespace Hardcodet.Util.Logging
{
  /// <summary>
  /// A very simple implementation of <see cref="ILogger"/>
  /// that outputs all messages to the system console.
  /// </summary>
  public class ConsoleLogger : LoggerBase
  {
    /// <summary>
    /// Logs a given item to the console.
    /// </summary>
    /// <param name="item">The item to be logged.</param>
    /// <exception cref="ArgumentNullException">If <paramref name="item"/>
    /// is a null reference.</exception>
    public override void Log(LogItem item)
    {
      if (item == null) throw new ArgumentNullException("item");
      Console.Out.WriteLine(item.ToLogMessage());
    }

  }
}

using Microsoft.Practices.EnterpriseLibrary.Logging;

namespace Hardcodet.Util.Logging.EntLibFacade
{
  /// <summary>
  /// An implementation of the <see cref="ILogger"/>
  /// interface which outputs logged data using
  /// the <see cref="Logger"/> of the MS Enterprise
  /// Library.
  /// </summary>
  public class EnterpriseLibraryLogger : LoggerBase
  {

    /// <summary>
    /// Writes a log entry to the Enterprise Library's
    /// logging block. Output depends on the logging
    /// block's configuration.
    /// </summary>
    /// <param name="item">An log item which encapsulates
    /// information to be logged.</param>
    public override void Log(LogItem item)
    {
      LogEntry entry = ConvertLogItem(item);
      Logger.Write(entry);
    }

    /// <summary>
    /// Creates a <c>LogEntry</c> instance which can be processed
    /// by the Enterprise Library based on a given log item. 
    /// </summary>
    /// <param name="item">An log item which encapsulates information
    /// to be logged.</param>
    /// <returns>An Enterprise Library item which corresponds
    /// to the submitted <c>LogItem</c>.</returns>
    private static LogEntry ConvertLogItem(LogItem item)
    {
      //assign properties
      LogEntry entry = new LogEntry();
      entry.Message = item.Message;
      entry.Title = item.Title;
      entry.AddErrorMessage(item.ErrorMessage);
      entry.EventId = item.EventId;
      entry.Priority = item.Priority;
      entry.Severity = item.Severity;
      entry.TimeStamp = item.TimeStamp;

      foreach (string category in item.Categories)
      {
        item.Categories.Add(category);
      }

      return entry;
    }

  }
}

<Image
  Source="..\Shared\Images\HelpSmall.png"
  ToolTip="{ext:Info Title=ShareNameTitleToolTip, Body=ShareNameInfoToolTip}"
  />

<Image Source="..\Shared\Images\HelpSmall.png">
  <Image.ToolTip>
    <MyToolTipControl Header="My Title" Body="This is a ToolTip" />
  </Image.ToolTip>
</Image>

/// <summary>
/// A markup extension that returns a
/// <see cref="InfoPopup"/> control preconfigured
/// with header and text information according to the
/// <see cref="Title"/> and <see cref="Body"/>
/// properties.
/// </summary>
public class Info : MarkupExtension
{
  /// <summary>
  /// Either a title text or a resource key that can be used
  /// to look up the title.
  /// </summary>
  public string Title { get; set; }

  /// <summary>
  /// Either a tooltips' main text or a resource key that can be used
  /// to look up the text.
  /// </summary>
  public string Body { get; set; }

  /// <summary>
  /// Empty default constructor.
  /// </summary>
  public Info()
  {
  }

  /// <summary>
  /// Inits the <see cref="Info"/> markup extension
  /// with the title and body.
  /// </summary>
  public Info(string title, string body)
  {
    Title = title;
    Body = body;
  }

  /// <summary>
  /// Performs a lookup for the defined <see cref="Title"/> and
  /// <see cref="Info"/> and creates the tooltip control.
  /// </summary>
  /// <returns>
  /// A tooltip control.
  /// </returns>
  public override object ProvideValue(IServiceProvider serviceProvider)
  {
    //create the user control that 
    InfoPopup popup = new InfoPopup();

    if (!String.IsNullOrEmpty(Title))
    {
      //look up title - if the string is not a
      //resource key, use it directly
      var result = Resources.ResourceManager.GetObject(Title) ?? Title;
      popup.HeaderText = (string)result;
    }

    if (!String.IsNullOrEmpty(Body))
    {
      //look up body text - if the string is not a
      //resource key, use it directly
      var result = Resources.ResourceManager.GetObject(Body) ?? Body;
      popup.BodyText = (string)result;
    }

    //create tooltip and make sure only the content is visible
    ToolTip tt = new ToolTip();
    tt.HasDropShadow = false;
    tt.BorderThickness = new Thickness(0);
    tt.Background = Brushes.Transparent;
    tt.Content = popup;

    return tt;
  }
}

<Window ...>
  <Grid>
    <Grid.Resources>
      <r:RibbonCommand
        x:Key="MyCommand"
        Executed="OnRibbonClicked"
        LabelTitle="Click Me" />
    </Grid.Resources>

    <!-- a ribbon that only displays a command in the quick access toolbar -->
    <r:Ribbon>
      <r:Ribbon.QuickAccessToolBar>
        <r:RibbonQuickAccessToolBar>
          <r:RibbonButton
            Command="{StaticResource MyCommand}"
            r:RibbonQuickAccessToolBar.Placement="InToolBar" />
        </r:RibbonQuickAccessToolBar>
      </r:Ribbon.QuickAccessToolBar>
    </r:Ribbon>
  </Grid>
</Window>

private void OnRibbonClicked(object sender, ExecutedRoutedEventArgs e)
{
  MessageBox.Show("Ribbon command executing.");
}

///<summary>
/// Base class for custom <see cref="RibbonCommand"/>
/// implementations.
///</summary>
public abstract class RibbonCommandBase : RibbonCommand
{
  /// <summary>
  /// Creates the command and registers weak event listeners.
  /// </summary>
  protected RibbonCommandBase()
  {
    Executed += OnExecute;
    CanExecute += OnCanExecute;
  }

  /// <summary>
  /// Determines whether the command can be executed or not.
  /// The default implementation always allows that.
  /// </summary>
  protected virtual void OnCanExecute(object sender, CanExecuteRoutedEventArgs e)
  {
    e.CanExecute = true;
  }

  /// <summary>
  /// Command implementation - executes command logic.
  /// </summary>
  protected abstract void OnExecute(object sender, ExecutedRoutedEventArgs e);
}

public class MessageCommand : RibbonCommandBase
{
  protected override void OnExecute(object sender, ExecutedRoutedEventArgs e)
  {
    MessageBox.Show("Ribbon command executing.");
  }
}

<!-- Custom command - can be declared in a resource dictionary -->
<cmd:MessageCommand x:Key="MyCommand"
                    LabelTitle="Click Me"
                    SmallImageSource="About.png"
/>

public static byte[] Encrypt(byte[] data)
{
  var scope = DataProtectionScope.CurrentUser;
  return ProtectedData.Protect(data, null, scope);
}

string password = "hello world";
string encrypted = password.Encrypt();

string plainText = encrypted.Decrypt();

[Test]
public void Encryption_And_Decryption_Cycle_Should_Return_Original_Value()
{
  string plainText = "this is a password";

  //encrypt plain text
  string cipher = plainText.Encrypt();
  Assert.AreNotEqual(plainText, cipher);

  //decrypt cipher into managed string
  string decrypted = cipher.Decrypt();
  Assert.AreEqual(plainText, decrypted);

  //create a SecureString from the plain text
  SecureString plainSecure = plainText.ToSecureString();

  //test unwrapping of a SecureString
  Assert.AreEqual(plainText, plainSecure.Unwrap());

  //encrypt the string that is wrapped into the SecureString
  string cipherFromSecure = plainSecure.Encrypt();

  //decrypt the cipher that was created from the the SecureString
  Assert.AreEqual(plainText, cipherFromSecure.Decrypt());
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Security;
using System.Security.Cryptography;
using System.Text;

namespace Hardcodet.NetDrives.Platform
{
  /// <summary>
  /// Provides extension methods that deal with
  /// string encryption/decryption and
  /// <see cref="SecureString"/> encapsulation.
  /// </summary>
  public static class SecurityExtensions
  {
    /// <summary>
    /// Specifies the data protection scope of the DPAPI.
    /// </summary>
    private const DataProtectionScope Scope = DataProtectionScope.CurrentUser;

    /// <summary>
    /// Encrypts a given password and returns the encrypted data
    /// as a base64 string.
    /// </summary>
    /// <param name="plainText">An unencrypted string that needs
    /// to be secured.</param>
    /// <returns>A base64 encoded string that represents the encrypted
    /// binary data.
    /// </returns>
    /// <remarks>This solution is not really secure as we are
    /// keeping strings in memory. If runtime protection is essential,
    /// <see cref="SecureString"/> should be used.</remarks>
    /// <exception cref="ArgumentNullException">If <paramref name="plainText"/>
    /// is a null reference.</exception>
    public static string Encrypt(this string plainText)
    {
      if (plainText == null) throw new ArgumentNullException("plainText");

      //encrypt data
      var data = Encoding.Unicode.GetBytes(plainText);
      byte[] encrypted = ProtectedData.Protect(data, null, Scope);

      //return as base64 string
      return Convert.ToBase64String(encrypted);
    }

    /// <summary>
    /// Decrypts a given string.
    /// </summary>
    /// <param name="cipher">A base64 encoded string that was created
    /// through the <see cref="Encrypt(string)"/> or
    /// <see cref="Encrypt(SecureString)"/> extension methods.</param>
    /// <returns>The decrypted string.</returns>
    /// <remarks>Keep in mind that the decrypted string remains in memory
    /// and makes your application vulnerable per se. If runtime protection
    /// is essential, <see cref="SecureString"/> should be used.</remarks>
    /// <exception cref="ArgumentNullException">If <paramref name="cipher"/>
    /// is a null reference.</exception>
    public static string Decrypt(this string cipher)
    {
      if (cipher == null) throw new ArgumentNullException("cipher");

      //parse base64 string
      byte[] data = Convert.FromBase64String(cipher);

      //decrypt data
      byte[] decrypted = ProtectedData.Unprotect(data, null, Scope);
      return Encoding.Unicode.GetString(decrypted);
    }

    /// <summary>
    /// Encrypts the contents of a secure string.
    /// </summary>
    /// <param name="value">An unencrypted string that needs
    /// to be secured.</param>
    /// <returns>A base64 encoded string that represents the encrypted
    /// binary data.
    /// </returns>
    /// <exception cref="ArgumentNullException">If <paramref name="value"/>
    /// is a null reference.</exception>
    public static string Encrypt(this SecureString value)
    {
      if (value == null) throw new ArgumentNullException("value");

      IntPtr ptr = Marshal.SecureStringToCoTaskMemUnicode(value);
      try
      {
        char[] buffer = new char[value.Length];
        Marshal.Copy(ptr, buffer, 0, value.Length);

        byte[] data = Encoding.Unicode.GetBytes(buffer);
        byte[] encrypted = ProtectedData.Protect(data, null, Scope);

        //return as base64 string
        return Convert.ToBase64String(encrypted);
      }
      finally
      {
        Marshal.ZeroFreeCoTaskMemUnicode(ptr);
      }
    }

    /// <summary>
    /// Decrypts a base64 encrypted string and returns the decrpyted data
    /// wrapped into a <see cref="SecureString"/> instance.
    /// </summary>
    /// <param name="cipher">A base64 encoded string that was created
    /// through the <see cref="Encrypt(string)"/> or
    /// <see cref="Encrypt(SecureString)"/> extension methods.</param>
    /// <returns>The decrypted string, wrapped into a
    /// <see cref="SecureString"/> instance.</returns>
    /// <exception cref="ArgumentNullException">If <paramref name="cipher"/>
    /// is a null reference.</exception>
    public static SecureString DecryptSecure(this string cipher)
    {
      if (cipher == null) throw new ArgumentNullException("cipher");

      //parse base64 string
      byte[] data = Convert.FromBase64String(cipher);

      //decrypt data
      byte[] decrypted = ProtectedData.Unprotect(data, null, Scope);

      SecureString ss = new SecureString();

      //parse characters one by one - doesn't change the fact that
      //we have them in memory however...
      int count = Encoding.Unicode.GetCharCount(decrypted);
      int bc = decrypted.Length/count;
      for (int i = 0; i < count; i++)
      {
        ss.AppendChar(Encoding.Unicode.GetChars(decrypted, i*bc, bc)[0]);
      }

      //mark as read-only
      ss.MakeReadOnly();
      return ss;
    }

    /// <summary>
    /// Wraps a managed string into a <see cref="SecureString"/> 
    /// instance.
    /// </summary>
    /// <param name="value">A string or char sequence that 
    /// should be encapsulated.</param>
    /// <returns>A <see cref="SecureString"/> that encapsulates the
    /// submitted value.</returns>
    /// <exception cref="ArgumentNullException">If <paramref name="value"/>
    /// is a null reference.</exception>
    public static SecureString ToSecureString(this IEnumerable<char> value)
    {
      if (value == null) throw new ArgumentNullException("value");

      var secured = new SecureString();

      var charArray = value.ToArray();
      for (int i = 0; i < charArray.Length; i++)
      {
        secured.AppendChar(charArray[i]);
      }

      secured.MakeReadOnly();
      return secured;
    }

    /// <summary>
    /// Unwraps the contents of a secured string and
    /// returns the contained value.
    /// </summary>
    /// <param name="value"></param>
    /// <returns></returns>
    /// <remarks>Be aware that the unwrapped managed string can be
    /// extracted from memory.</remarks>
    /// <exception cref="ArgumentNullException">If <paramref name="value"/>
    /// is a null reference.</exception>
    public static string Unwrap(this SecureString value)
    {
      if (value == null) throw new ArgumentNullException("value");

      IntPtr ptr = Marshal.SecureStringToCoTaskMemUnicode(value);
      try
      {
        return Marshal.PtrToStringUni(ptr);
      }
      finally
      {
        Marshal.ZeroFreeCoTaskMemUnicode(ptr);
      }
    }

    /// <summary>
    /// Checks whether a <see cref="SecureString"/> is either
    /// null or has a <see cref="SecureString.Length"/> of 0.
    /// </summary>
    /// <param name="value">The secure string to be inspected.</param>
    /// <returns>True if the string is either null or empty.</returns>
    public static bool IsNullOrEmpty(this SecureString value)
    {
      return value == null || value.Length == 0;
    }

    /// <summary>
    /// Performs bytewise comparison of two secure strings.
    /// </summary>
    /// <param name="value"></param>
    /// <param name="other"></param>
    /// <returns>True if the strings are equal.</returns>
    public static bool Matches(this SecureString value, SecureString other)
    {
      if (value == null && other == null) return true;
      if (value == null || other == null) return false;
      if (value.Length != other.Length) return false;
      if (value.Length == 0 && other.Length == 0) return true;

      IntPtr ptrA = Marshal.SecureStringToCoTaskMemUnicode(value);
      IntPtr ptrB = Marshal.SecureStringToCoTaskMemUnicode(other);
      try
      {
        //parse characters one by one - doesn't change the fact that
        //we have them in memory however...
        byte byteA = 1;
        byte byteB = 1;

        int index = 0;
        while (((char)byteA) != '\0' && ((char)byteB) != '\0')
        {
          byteA = Marshal.ReadByte(ptrA, index);
          byteB = Marshal.ReadByte(ptrB, index);
          if (byteA != byteB) return false;
          index += 2;
        }

        return true;
      }
      finally
      {
        Marshal.ZeroFreeCoTaskMemUnicode(ptrA);
        Marshal.ZeroFreeCoTaskMemUnicode(ptrB);
      }
    }
  }
}

public void TestBinding(Student student)
{
  string cityName = "";

  //synchronize the cityName field with the City property of the school's address
  var binding = LambdaBinding.BindOneWay(
      () => student.School.Address.City,
      () => cityName);

  //change the property on the School object
  student.School.Address.City = "Sin City";

  //the binding expression updated the local variable
  Assert.AreEqual("Sin City", cityName);
}

[Test]
public void Updating_Intermediary_Object_Should_Update_Target(Student student)
{
  string cityName = "";

  //synchronize the cityName field with the City property of the school's address
  var binding = LambdaBinding.BindOneWay(
      () => student.School.Address.City,
      () => cityName);

  //change bound City property -> triggers update of the local variable
  student.School.Address.City = "Paris";
  Assert.AreEqual("Paris", cityName);

  //create a completely different school instance
  School englishSchool = new School();
  englishSchool.Address = new Address {City = "London"};

  //assign the new school to the student
  student.School = englishSchool;

  //setting the School property also triggered the binding
  Assert.AreEqual("London", cityName);
}

[Test]
public void Boolean_Should_Be_Converted_To_Visibility()
{
  //create a hidden window
  Window window = new Window { Visibility = Visibiliy.Collapsed };

  //create a view model
  MyViewModel viewModel = new MyViewModel { IsVisible = false };

  //create binding that casts the Visibility into a boolean
  LambdaBinding.BindOneWay(
      () => viewModel.IsVisible,
      () => window.Visibility,
      b => b == true ? Visibility.Visible : Visibility.Collapsed;

  //a change in the ViewModel shows/hides the window
  viewModel.IsVisible = true;

  Assert.AreEqual(Visibility.Visible, window.Visibility);
}

[Test]
public void Updates_Should_Work_Both_Ways()
{
  //create two-way binding
  var binding = LambdaBinding.BindTwoWay(
    () => FirstStudent.Name,
    () => SecondStudent.Name);

  //change property on source
  FirstStudent.Name = "Peter";
  Assert.AreEqual("Peter", SecondStudent.Name);

  //change property on target
  SecondStudent.Name = "Parker";
  Assert.AreEqual("Parker", FirstStudent.Name);
}

//bind a boolean property to a control's Visibility property
var binding = LambdaBinding.BindTwoWay(
    () => ModelItem.IsEnabled,
    () => MyControl.IsVisible,
    b => b == true ? Visibility.Visible : Visibiliy.Collapsed
    v => v == Visibility.Visible ? true : false);

//a local field to be updated
private string schoolCity;

[Test]
public void Breaking_The_Chain_Should_Assign_Default_Value_To_Target_If_Specified()
{
  var binding = LambdaBinding.BindOneWay(
      () => Student.School.Address.City,
      () => schoolCity,
      "[No City]");

  //break the source chain
  Student.School = null;

  //the default value was assigned to the target
  Assert.AreEqual("[No City]", schoolCity);
}

<!-- the popup that is displayed if user moves rows -->
<Popup
  x:Name="popup1"
  IsHitTestVisible="False"
  Placement="RelativePoint"
  PlacementTarget="{Binding ElementName=me}"
  AllowsTransparency="True">
  <Border
    BorderBrush="{DynamicResource CellBorderBrush}"
    BorderThickness="2"
    Background="White"
    Opacity="0.75">
    <StackPanel
      Orientation="Horizontal"
      Margin="4,3,8,3">
      <Image
        Source="/Shared/Images/DragInsert.png"
        Width="16"
        Height="16" />
      <TextBlock
        Style="{DynamicResource DefaultLabel}"
        FontWeight="Bold"
        VerticalAlignment="Center"
        Text="{Binding ElementName=me, Path=DraggedItem.Name}"
        Margin="8,0,0,0" />
    </StackPanel>
  </Border>
</Popup>

<dg:DataGrid
  BeginningEdit="OnBeginEdit"
  CellEditEnding="OnEndEdit"
  .. />

/// <summary>
/// State flag which indicates whether the grid is in edit
/// mode or not.
/// </summary>
public bool IsEditing { get; set; }

private void OnBeginEdit(object sender, DataGridBeginningEditEventArgs e)
{
  IsEditing = true;
  //in case we are in the middle of a drag/drop operation, cancel it...
  if (IsDragging) ResetDragDrop();
}

private void OnEndEdit(object sender, DataGridCellEditEndingEventArgs e)
{
  IsEditing = false;
}

private void OnMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
  //exit if in edit mode
  if (IsEditing) return;

  //find the clicked row
  var row = UIHelpers.TryFindFromPoint<DataGridRow>((UIElement) sender,
                                                    e.GetPosition(shareGrid));
  if (row == null) return;

  //set flag that indicates we're capturing mouse movements
  IsDragging = true;
  DraggedItem = (IShareConfiguration) row.Item;
}

/// <summary>
/// Completes a drag/drop operation.
/// </summary>
private void OnMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
  if (!IsDragging || IsEditing)
  {
    return;
  }

  //get the target item
  ShareConfiguration targetItem = (ShareConfiguration) shareGrid.SelectedItem;

  if (targetItem == null || !ReferenceEquals(DraggedItem, targetItem))
  {
    //remove the source from the list
    ShareList.Remove(DraggedItem);

    //get target index
    var targetIndex = ShareList.IndexOf(targetItem);

    //move source at the target's location
    ShareList.Insert(targetIndex, DraggedItem);

    //select the dropped item
    shareGrid.SelectedItem = DraggedItem;
  }

  //reset
  ResetDragDrop();
}

/// <summary>
/// Completes a drag/drop operation.
/// </summary>
private void OnMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
  if (!IsDragging || IsEditing || shareGrid.SelectedItem == null)
  {
    return;
  }

  //get the target item
  IShareConfiguration targetItem = (IShareConfiguration)shareGrid.SelectedItem;

  if (!ReferenceEquals(DraggedItem, targetItem))
  {
    //the actual business logic that works on source and target
  }

  //reset
  ResetDragDrop();
}

/// <summary>
/// Closes the popup and resets the
/// grid to read-enabled mode.
/// </summary>
private void ResetDragDrop()
{
  IsDragging = false;
  popup1.IsOpen = false;
  shareGrid.IsReadOnly = false;
}

<!-- fires even if the user does not click a given row -->
<dg:DataGrid
  dg:DataGridRow.MouseDoubleClick="OnDoubleClick" />

<!-- just register a listener on the grid -->
<dg:DataGrid
  MouseDoubleClick="OnDoubleClick" />

/// <summary>
/// Handles double-clicks on datagrid rows.
/// </summary>
private void OnDoubleClick(object sender, MouseButtonEventArgs e)
{
  //search the object hierarchy for a datagrid row
  DependencyObject source = (DependencyObject) e.OriginalSource;
  var row = UIHelpers.TryFindParent<DataGridRow>(source);

  //the user did not click on a row
  if (row == null) return;

  //[insert great code here...]

  e.Handled = true;
}

/// <summary>
/// Finds a parent of a given item on the visual tree.
/// </summary>
/// <typeparam name="T">The type of the queried item.</typeparam>
/// <param name="child">A direct or indirect child of the
/// queried item.</param>
/// <returns>The first parent item that matches the submitted
/// type parameter. If not matching item can be found, a null
/// reference is being returned.</returns>
public static T TryFindParent<T>(this DependencyObject child)                               where T : DependencyObject
{
  //get parent item
  DependencyObject parentObject = GetParentObject(child);

  //we've reached the end of the tree
  if (parentObject == null) return null;

  //check if the parent matches the type we're looking for
  T parent = parentObject as T;
  if (parent != null)
  {
    return parent;
  }
  else
  {
    //use recursion to proceed with next level
    return TryFindParent<T>(parentObject);
  }
}

/// <summary>
/// This method is an alternative to WPF's
/// <see cref="VisualTreeHelper.GetParent"/> method, which also
/// supports content elements. Keep in mind that for content element,
/// this method falls back to the logical tree of the element!
/// </summary>
/// <param name="child">The item to be processed.</param>
/// <returns>The submitted item's parent, if available. Otherwise
/// null.</returns>
public static DependencyObject GetParentObject(this DependencyObject child)
{
  if (child == null) return null;

  //handle content elements separately
  ContentElement contentElement = child as ContentElement;
  if (contentElement != null)
  {
    DependencyObject parent = ContentOperations.GetParent(contentElement);
    if (parent != null) return parent;

    FrameworkContentElement fce = contentElement as FrameworkContentElement;
    return fce != null ? fce.Parent : null;
  }

  //also try searching for parent in framework elements (such as DockPanel, etc)
  FrameworkElement frameworkElement = child as FrameworkElement;
  if (frameworkElement != null)
  {
    DependencyObject parent = frameworkElement.Parent;
    if (parent != null) return parent;
  }

  //if it's not a ContentElement/FrameworkElement, rely on VisualTreeHelper
  return VisualTreeHelper.GetParent(child);
}

<TextBox
    x:Name="name"
    Text="world" />

<TextBlock
    Text="{Binding ElementName=name,
                   Path=Text,
                   StringFormat=hello \{0\}}" />

//use resource file to create message
var msg = Resources.Ask_Whether_To_Connect_To_New_Share;
msg = String.Format(msg, configuration.Name);

//display dialog
MessageBoxResult doConnect = Dialogs.ShowYesNo(msg);

<!-- Display a formatted text -->
<TextBlock
  x:Name="Title"
  Text="{Binding Path=Name,
                 StringFormat={ext:Resource Ask_Whether_To_Connect_To_New_Share}}"

 />

/// <summary>
/// A markup extension that provides simple access to a given
/// entry in the application's <see cref="Resources"/> file.
/// </summary>
public class Resource : MarkupExtension
{
  /// <summary>
  /// The resource key to be used for the lookup.
  /// </summary>
  public string ResourceKey { get; set; }

  /// <summary>
  /// Inits the <see cref="Resource"/> markup extension
  /// with the key to be assigned.
  /// </summary>
  /// <param name="resourceKey">The resource key to be assigned.</param>
  public Resource(string resourceKey)
  {
    ResourceKey = resourceKey;
  }

  /// <summary>
  /// Performs a lookup for the defined <see cref="ResourceKey"/>.
  /// </summary>
  /// <returns>
  /// The value of the resource that is specified by the
  /// <see cref="ResourceKey"/> property. If the property is not
  /// set, a null reference is returned.
  /// </returns>
  public override object ProvideValue(IServiceProvider serviceProvider)
  {
    if (String.IsNullOrEmpty(ResourceKey)) return null;
    return Resources.ResourceManager.GetObject(ResourceKey);
  }
}

public void TestElapsedTime()
{
  DateTime start = DateTime.Now;

  //do some work

  DateTime end = DateTime.Now;
  double elapsedTime = end.Subtract(start).TotalMilliseconds;
  Console.Out.WriteLine("Work took {0} milliseconds", elapsedTime);
}

/// <summary>
/// A guard that can be used to measure the time
/// used for a given process by simply wrapping it
/// in a using statement.
/// </summary>
public class TimeGuard : IDisposable
{
  private readonly Action<double> action;
  private readonly DateTime startTime;

  /// <summary>
  /// Creates the guard with a given action that receives the
  /// elapsed time in milliseconds.
  /// </summary>
  /// <param name="setDelta">The action that is being invoked
  /// with time (in milleconds) that was taken between construction
  /// of this instance until disposal.</param>
  /// <exception cref="ArgumentNullException">If <paramref name="setDelta"/>
  /// is a null reference.</exception>
  public TimeGuard(Action<double> setDelta)
  {
    if (setDelta == null) throw new ArgumentNullException("setDelta");

    action = setDelta;
    startTime = DateTime.Now;
  }

  /// <summary>
  /// Calculates the elapsed time since construction
  /// and submits the delta to the <see cref="action"/>
  /// action.
  /// </summary>
  public void Dispose()
  {
    var now = DateTime.Now;
    action(now.Subtract(startTime).TotalMilliseconds);
  }
}

public void TestElapsedTime()
{
  double elapsedTime = 0;
  using (new TimeGuard(t => elapsedTime = t))
  {
    //do some work
  }

  Console.Out.WriteLine("Work took {0} milliseconds", elapsedTime);
}

[Test]
public void TestElapsedTime()
{
  using (new TimeGuard(t => Assert.Less(t, 500)))
  {
    //do some work here that should take less than 500 ms
  }
}

//check status flags
TestStatus status = GetStatus();
if (status == TestStatus.Preparing ||
    status == TestStatus.Running ||
    status == TestStatus.PostDelay)
{
  ...
}

/// <summary>
/// Checks a list of candidates for equality to a given
/// reference value.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="value">The evaluated value.</param>
/// <param name="candidates">A liste of possible values that are
/// regarded valid.</param>
/// <returns>True if one of the submitted <paramref name="candidates"/>
/// matches the evaluated value. If the <paramref name="candidates"/>
/// parameter itself is null, too, the method returns false as well,
/// which allows to check with null values, too.</returns>
/// <exception cref="ArgumentNullException">If <paramref name="candidates"/>
/// is a null reference.</exception>
public static bool Is<T>(this T value, params T[] candidates)
{
  if (candidates == null) return false;

  foreach (var t in candidates)
  {
    if (value.Equals(t)) return true;
  }

  return false;
}

if (status.Is(TestStatus.Preparing, TestStatus.Running, TestStatus.PostDelay)
{
  ...
}

string name = ...
if (name.Is("foo", "bar"))
{
  //foobar!
}

<ComboBox
  x:Name="cboParentUser"
  ItemsSource="{Binding Path=Order.Store.Users, ElementName=me, Mode=Default}"
  SelectedItem="{Binding Path=Order.ParentUser, ElementName=me, Mode=Default}"
  IsEditable="False"
  DisplayMemberPath="UserName" />

<ComboBox
  x:Name="cboParentUser"
  SelectedItem="{Binding Path=Order.ParentUser, ElementName=me, Mode=Default}"
  ItemsSource="{Binding Path=Order.Store.Users, ElementName=me, Mode=Default}"
  IsEditable="False"
  DisplayMemberPath="UserName" />