主窗体Form1是一个ListBox，单击选中某列时，弹出窗体Form2，Form2中两个控件，一个是TextBox，显示选中的该列的文本，另一个是按钮，点击时将修改后的值回传，且在Form1中修改相应的列的文本，同时Form2关闭。

 C#窗体间通讯方法一：传值

public partial class Form2 : Form     
    {     
        private string text;     
        private ListBox lb;     
        private int index;     
    
       //构造函数接收三个参数：选中行文本，ListBox控件，选中行索引     
        public Form2(string text,ListBox lb,int index)     
        {     
            this.text = text;     
            this.lb = lb;     
            this.index = index;     
            InitializeComponent();     
            this.textBox1.Text = text;     
        }     
    
        private void btnChange_Click(object sender, EventArgs e)     
        {                
            string text = this.textBox1.Text;     
            this.lb.Items.RemoveAt(index);     
            this.lb.Items.Insert(index, text);     
            this.Close();     
        }     
    }   

public partial class Form1 :Form     
    {     
        int index = 0;     
        string text = null;     
        public Form1()     
        {     
            InitializeComponent();     
        }     
    
        private void listBox1_SelectedIndexChanged(object sender, EventArgse)     
        {                 
            if (this.listBox1.SelectedItem != null)     
            {     
                text = this.listBox1.SelectedItem.ToString();     
                index = this.listBox1.SelectedIndex;     
    
               //构造Form2同时传递参数     
                Form2 form2 = new Form2(text, listBox1, index);     
                form2.ShowDialog();     
            }     
       }   

 C#窗体间通讯方法二：事件回调

//定义一个需要string类型参数的委托         
public delegate void MyDelegate(string text);         
public partial class Form2 :Form1     
    {         
       //定义该委托的事件     
        public event MyDelegate MyEvent;     
        public Form2(string text)     
        {      
            InitializeComponent();     
            this.textBox1.Text = text;     
       }     
       private void btnChange_Click(object sender, EventArgs e)                   
       {     

           //触发事件，并将修改后的文本回传     
           MyEvent(this.textBox1.Text);     
           this.Close();     
        }     
   }   

public partial class Form1 :Form     
    {     
        public int index = 0;     
        public string text = null;     
        public Form1()     
        {     
            InitializeComponent();     
        }     
    
        private void listBox1_SelectedIndexChanged(object sender, EventArgse)     
        {     
            if (this.listBox1.SelectedItem != null)     
            {     
                text = this.listBox1.SelectedItem.ToString();     
                index = this.listBox1.SelectedIndex;     
                Form2 form2 = new Form2(text);     
    
               //注册form2_MyEvent方法的MyEvent事件     
                form2.MyEvent += new MyDelegate(form2_MyEvent);     
                form2.Show();     
            }     
        }     
    
       //处理     
    
        void form2_MyEvent(string text)     
        {     
            this.listBox1.Items.RemoveAt(index);     
            this.listBox1.Items.Insert(index, text);     
       }     
   }