Use Application Command to edit RichTextBox


   
  
<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();
        }
    }
}