<Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="WPF " Height="300" Width="300"> <DockPanel LastChildFill="True"> <TextBox DockPanel.Dock="Top" PreviewTextInput="TextBox_TextEvent"/> <TextBox Name="txtLog" HorizontalAlignment="Stretch" IsReadOnly="True" VerticalScrollBarVisibility="Visible"/> </DockPanel> </Window> //File:Window.xaml.cs using System; using System.Windows; using System.Windows.Input; namespace WpfApplication1 { public partial class Window1 : Window { public Window1() { InitializeComponent(); } private void TextBox_TextEvent(object sender,TextCompositionEventArgs e) { String msg = String.Format("{0} - {1} ", e.RoutedEvent.Name, e.Text); txtLog.Text += msg; txtLog.ScrollToEnd(); } } }