WPF C#

    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="WPF" Height="350" Width="500">
    
        
            
                
                    
                
            

            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
        
                             HorizontalScrollBarVisibility="Visible" 
                     VerticalScrollBarVisibility="Visible">
            
                
                    paragraph
                
                
                    paragraph
                
                A List
                
                    
                        
                            Bold List Item
                        

                    

                    
                        
                            Italic List Item
                        

                    

                    
                        
                            Underlined List Item
                        

                    

                

            

        
    


//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();
        }
    }
}