//清空菜单项        private void CleaarMenuMain()        {            foreach (ToolStripMenuItem item in menuMain.Items)            {                item.DropDownItems.Clear();                item.Visible = true;            }        }

//初始化菜单        private void InitMemuMain()        {            CleaarMenuMain();            ToolStripMenuItem tsmi;            ToolStripMenuItem tsmiSub;            //添加菜单            tsmi = new ToolStripMenuItem("a");            tsmiSub = new ToolStripMenuItem("a1", null, tsmiSub_Click, "tsmiName");            tsmi.DropDownItems.Add(tsmiSub);            tsmiSub = new ToolStripMenuItem("a2", null, null, "tsmiName");            tsmi.DropDownItems.Add(tsmiSub);            menuMain.Items.Add(tsmi);          //添加菜单            tsmi = new ToolStripMenuItem("b");            tsmiSub = new ToolStripMenuItem("b1", null, tsmiSub_Click, "tsmiName");            tsmi.DropDownItems.Add(tsmiSub);            tsmiSub = new ToolStripMenuItem("b2", null, null, "tsmiName");            tsmi.DropDownItems.Add(tsmiSub);            menuMain.Items.Add(tsmi);        }

 //菜单点击事件具体实现        private void tsmiSub_Click(object sender, EventArgs e)        {            MessageBox.Show("!!!!!!");        }