public class LookupExtension : BindingDecoratorBase
{//A property that can be set in XAMLpublic string LookupKey { get; set; }public override object ProvideValue(IServiceProvider provider){//delegate binding creation etc. to the base classobject val = base.ProvideValue(provider);//try to get bound items for our custom work
    DependencyObject targetObject;DependencyProperty targetProperty;bool status = TryGetTargetItems(provider, out targetObject,out targetProperty);if (status){//associate an input listener with the control
      InputHandler.RegisterHandler(targetObject, LookupKey);}return val;}
}

<TextBox Name="txtZipCode"><TextBox.Text><local:LookupExtension Source="{StaticResource MyAddress}"Path="ZipCode"LookupKey="F5" /></TextBox.Text>
</TextBox>

<TextBox Text="{z:DelayBinding Path=SearchText, Delay='00:00:01'}" />

[MarkupExtensionReturnType(typeof(object))]
public class DelayBindingExtension : MarkupExtension
{public DelayBindingExtension(){Delay = TimeSpan.FromSeconds(0.5);}public DelayBindingExtension(PropertyPath path) : this(){Path = path;}public IValueConverter Converter { get; set; }public object ConverterParamter { get; set; }public string ElementName { get; set; }public RelativeSource RelativeSource { get; set; }public object Source { get; set; }public bool ValidatesOnDataErrors { get; set; }public bool ValidatesOnExceptions { get; set; }public TimeSpan Delay { get; set; }[ConstructorArgument("path")]public PropertyPath Path { get; set; }[TypeConverter(typeof(CultureInfoIetfLanguageTagConverter))]public CultureInfo ConverterCulture { get; set; }public override object ProvideValue(IServiceProvider serviceProvider){var valueProvider = serviceProvider.GetService(typeof (IProvideValueTarget)) as IProvideValueTarget;if (valueProvider != null){var bindingTarget = valueProvider.TargetObject as DependencyObject;var bindingProperty = valueProvider.TargetProperty as DependencyProperty;if (bindingProperty == null || bindingTarget == null){throw new NotSupportedException(string.Format("The property '{0}' on target '{1}' is not valid for a DelayBinding. The DelayBinding target must be a DependencyObject, "+ "and the target property must be a DependencyProperty.", valueProvider.TargetProperty, valueProvider.TargetObject));}var binding = new Binding();binding.Path = Path;binding.Converter = Converter;binding.ConverterCulture = ConverterCulture;binding.ConverterParameter = ConverterParamter;if (ElementName != null) binding.ElementName = ElementName;if (RelativeSource != null) binding.RelativeSource = RelativeSource;if (Source != null) binding.Source = Source;binding.ValidatesOnDataErrors = ValidatesOnDataErrors;binding.ValidatesOnExceptions = ValidatesOnExceptions;return DelayBinding.SetBinding(bindingTarget, bindingProperty, Delay, binding);}return null;}
}

public class DelayBinding
{private readonly BindingExpressionBase _bindingExpression;private readonly DispatcherTimer _timer;protected DelayBinding(BindingExpressionBase bindingExpression, DependencyObject bindingTarget, DependencyProperty bindingTargetProperty, TimeSpan delay){_bindingExpression = bindingExpression;// Subscribe to notifications for when the target property changes. This event handler will be // invoked when the user types, clicks, or anything else which changes the target propertyvar descriptor = DependencyPropertyDescriptor.FromProperty(bindingTargetProperty, bindingTarget.GetType());descriptor.AddValueChanged(bindingTarget, BindingTarget_TargetPropertyChanged);// Add support so that the Enter key causes an immediate commitvar frameworkElement = bindingTarget as FrameworkElement;if (frameworkElement != null){frameworkElement.KeyUp += BindingTarget_KeyUp;}// Setup the timer, but it won't be started until changes are detected_timer = new DispatcherTimer();_timer.Tick += Timer_Tick;_timer.Interval = delay;}private void BindingTarget_KeyUp(object sender, KeyEventArgs e){if (e.Key != Key.Enter) return;_timer.Stop();_bindingExpression.UpdateSource();}private void BindingTarget_TargetPropertyChanged(object sender, EventArgs e){_timer.Stop();_timer.Start();}private void Timer_Tick(object sender, EventArgs e){_timer.Stop();_bindingExpression.UpdateSource();}public static object SetBinding(DependencyObject bindingTarget, DependencyProperty bindingTargetProperty, TimeSpan delay, Binding binding){// Override some specific settings to enable the behavior of delay bindingbinding.Mode = BindingMode.TwoWay;binding.UpdateSourceTrigger = UpdateSourceTrigger.Explicit;// Apply and evaluate the bindingvar bindingExpression = BindingOperations.SetBinding(bindingTarget, bindingTargetProperty, binding);// Setup the delay timer around the binding. This object will live as long as the target element lives, since it subscribes to the changing event, // and will be garbage collected as soon as the element isn't required (e.g., when it's Window closes) and the timer has stopped.new DelayBinding(bindingExpression, bindingTarget, bindingTargetProperty, delay);// Return the current value of the binding (since it will have been evaluated because of the binding above)return bindingTarget.GetValue(bindingTargetProperty);}
}