winform右键菜单

public partial class Form1 : Form  
    {  
        ContextMenuStrip cms;  
        Bitmap bm ;  
        public Form1()  
        {  
            InitializeComponent();  
        }  
        private void Form1_MouseDown(object sender, MouseEventArgs e)  
        {  
              
            if (e.Button == MouseButtons.Right)  
            {  
                if (cms.Items.Count > 0)  
                {  
                    cms.Items.Clear();  
                }  
                //带图表项  
                cms.Items.Add("tubiao",bm,new EventHandler(tubiao_Handler));  
                cms.Items.Add("mouseright1");  
                cms.Items.Add("-");  
                cms.Items.Add("mouseright2");  
                cms.Items.Add("-");  
                cms.Items.Add("mouseright3");  
            }  
            else 
            {  
                return;  
            }  
            //处理显示位置  
            int w= Width-e.X;  
            if (w < cms.Width)  
            {  
                cms.Show(this, e.X - cms.Width, e.Y);  
            }  
            else 
            {  
                cms.Show(this,e.X,e.Y);  
            }  
 
        }  
        public void tubiao_Handler(object sender, EventArgs e)  
        {  
            MessageBox.Show("this is tubiao", "tubiao", MessageBoxButtons.YesNo);  
        }  
        private void Form1_Load(object sender, EventArgs e)  
        {  
            cms = new ContextMenuStrip();  
            bm = new Bitmap("Resources/Icon1.ico");//图标存放位置  
        }  
    }