Как взаимодействовать Combobox c RichBox ?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
 
namespace RGPPU
{
    /// <summary>
    /// Логика взаимодействия для Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }
 
        private void Frame_Navigated(object sender, System.Windows.Navigation.NavigationEventArgs e)
        {
 
        }
 
        private void ScrollBar_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
        {
            
        }
 
        private void RichTextBox_Scroll(object sender, System.Windows.Controls.Primitives.ScrollEventArgs e)
        {
          
        }
 
        private void RichTextBox_TextChanged(object sender, TextChangedEventArgs e)
        {
 
        }
 
        private void ComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
           
        }
 
        private void TextBlock_SourceUpdated(object sender, DataTransferEventArgs e)
        {
 
        }
 
        private void TextBlock_SourceUpdated_1(object sender, DataTransferEventArgs e)
        {
 
        }
 
        private void TextBlock_SourceUpdated_2(object sender, DataTransferEventArgs e)
        {
 
        }
 
        private void ComboBox_SelectionChanged_1(object sender, SelectionChangedEventArgs e)
        {
 
         
        }
 
        private void TextBlock_Click(object sender, RoutedEventArgs e)
        {
 
        }
    }
}