<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="350" Width="500"> <DockPanel> <StackPanel DockPanel.Dock="Top" Orientation="Horizontal"> <StackPanel.Resources> <Style TargetType="{x:Type Button}"> <Setter Property="CommandTarget" Value="{Binding ElementName=rtbTextBox1}" /> </Style> </StackPanel.Resources> <Button Content="Clear" Name="btnClear" Click="btnClear_Click" /> <Separator Margin="5"/> <Button Content="Cu_t" Command="ApplicationCommands.Cut" /> <Button Content="_Copy" Command="ApplicationCommands.Copy" /> <Button Content="_Paste" Command="ApplicationCommands.Paste" /> <Separator Margin="5"/> <Button Content="_Undo" Command="ApplicationCommands.Undo" /> <Button Content="_Redo" Command="ApplicationCommands.Redo" /> <Separator Margin="5"/> <Button Content="_Bold" Command="EditingCommands.ToggleBold" /> <Button Content="_Italic" Command="EditingCommands.ToggleItalic" /> <Button Content="Underline" Command="EditingCommands.ToggleUnderline" /> <Separator Margin="5"/> <Button Content="_Right" Command="EditingCommands.AlignRight" /> <Button Content="C_enter" Command="EditingCommands.AlignCenter" /> <Button Content="_Left" Command="EditingCommands.AlignLeft" /> </StackPanel> <RichTextBox DockPanel.Dock="Bottom" Name="rtbTextBox1" HorizontalScrollBarVisibility="Visible" VerticalScrollBarVisibility="Visible"> <FlowDocument> <Paragraph FontSize="12"> paragraph </Paragraph> <Paragraph FontSize="15"> paragraph </Paragraph> <Paragraph FontSize="18">A List</Paragraph> <List> <ListItem> <Paragraph> <Bold>Bold List Item</Bold> </Paragraph> </ListItem> <ListItem> <Paragraph> <Italic>Italic List Item</Italic> </Paragraph> </ListItem> <ListItem> <Paragraph> <Underline>Underlined List Item</Underline> </Paragraph> </ListItem> </List> </FlowDocument> </RichTextBox> </DockPanel> </Window> //File:Window.xaml.cs using System.Windows; namespace WpfApplication1 { public partial class Window1 : Window { public Window1() { InitializeComponent(); } private void btnClear_Click(object sender, RoutedEventArgs e) { rtbTextBox1.SelectAll(); rtbTextBox1.Cut(); } } }