Making dynamic check boxes perform and action c#

I'm working on making a program give the ability to allow the user to set a target of an active window.

I have two problems with my code, perhaps someone can let me know if the path i've chosen is wrong or there is a better path.

1. The Window output is only showing 16 characters of the name of the process.

2. I have the check box listed but don't know how to dynamically assign them to do the change where it will make the TextBox.Text Change.

   using System;
   using System.Collections.Generic;
   using System.ComponentModel;
   using System.Data;
   using System.Drawing;
   using System.Linq;
   using System.Text;
   using System.Windows.Forms;
   using System.Diagnostics;
   using System.IO;
   using System.Runtime.InteropServices;
   
   
   namespace Workspace
   {
       public partial class Form5 : Form
       {
   
       string target = File.ReadAllText("./target.txt");
   
       public Form5()
       {
           InitializeComponent();
   
           //Shows current target in textbox.
           string target = File.ReadAllText("./target.txt");
           textBox1.Text = target;
   
           // Sets a starting point.
           int total_processes = 0;
   
           // Captures proccesses.
           Process[] processlist = Process.GetProcesses();
   
           //looks at all proccess to separate with titles.
           foreach (Process process in processlist)
           {
   
               //calculates total proccess with titles.
               if (!String.IsNullOrEmpty(process.MainWindowTitle))
               {
                   total_processes = total_processes + 1;
               }   
           }
   
           // Sets up string array total by number of processes with name.
   
   
              string[] stringArray = new string[total_processes];
   
               //Names each proccess array.
               int loopnum = 0;
               foreach (Process process in processlist)
               {
                   if (!String.IsNullOrEmpty(process.MainWindowTitle))
                   {                        
                   stringArray[loopnum] = process.MainWindowTitle;
                   loopnum = loopnum + 1;
                   }   
               }
   
           // Generates # of Radio buttons per proccess with name.
           System.Windows.Forms.RadioButton [] radioButtons = new System.Windows.Forms.RadioButton[total_processes];
   
               for (int i = 0; i < total_processes; ++i)
                   {                
                   radioButtons[i] = new RadioButton();                    
                   radioButtons[i].Text = stringArray[i];                    
                   radioButtons[i].Location = new System.Drawing.Point(10, 10 + i * 20);
                   radioButtons[i].CheckedChanged += new EventHandler(this.radioButtons_CheckChanged);
                   this.Controls.Add(radioButtons[i]);                    
               }
       }
   
       private void radioButtons_CheckChanged(object sender, EventArgs e)
       {
           // Dynamic Check box if checked changes textBox1.Text to radioButtons[i].Text
       }
   
       private void button1_Click(object sender, EventArgs e)
       {
           System.IO.StreamWriter file = new System.IO.StreamWriter("./target.txt");
           file.WriteLine(textBox1.Text);
           file.Close();
       }               
   }
   }