winform

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace 菜单和工具栏
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
#region  窗体载入

        // 窗体载入
        private void Form1_Load(object sender, EventArgs e)
        {
            // 状态栏ToolStripMenuItem处于【√】勾选状态
            状态栏ToolStripMenuItem.Checked = true;
            状态栏ToolStripMenuItem.CheckState = CheckState.Checked;
            // 设置 状态栏菜单的CheckOnClick 为 true, 当鼠标单击 状态栏菜单时,会根据CheckedChanged设置勾选状态
            // 即: 处于【√】时,取消勾选, 否则勾选
            状态栏ToolStripMenuItem.CheckOnClick = true;
            // 显示控件: statusStrip1
            statusStrip1.Visible = true;

            // 工具栏ToolStripMenuItem处于【√】勾选状态
            工具栏ToolStripMenuItem.Checked = true;
            工具栏ToolStripMenuItem.CheckState = CheckState.Checked;
            工具栏ToolStripMenuItem.CheckOnClick = true;
            toolStrip1.Visible = true;

            // 工具栏按钮的显示样式 : 图片+文字
            toolStripButton1.DisplayStyle = ToolStripItemDisplayStyle.ImageAndText;
            toolStripButton1.TextImageRelation = TextImageRelation.ImageBeforeText;     // 图片在文字前面

            toolStripButton2.DisplayStyle = ToolStripItemDisplayStyle.ImageAndText;
            toolStripButton2.TextImageRelation = TextImageRelation.ImageAboveText;      // 图片在文字上面

            toolStripButton3.DisplayStyle = ToolStripItemDisplayStyle.ImageAndText;
            toolStripButton3.TextImageRelation = TextImageRelation.Overlay;                     // 文字覆盖图片

            toolStripButton4.DisplayStyle = ToolStripItemDisplayStyle.ImageAndText;
            toolStripButton4.TextImageRelation = TextImageRelation.TextBeforeImage;    // 图片在文字后面

            toolStripButton5.DisplayStyle = ToolStripItemDisplayStyle.ImageAndText;
            toolStripButton5.TextImageRelation = TextImageRelation.TextAboveImage;      // 图片在文字下面

        }
#endregion

#region   退出菜单项
        private void 退出ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            // 关闭窗口
            this.Close();
        }
#endregion

#region 关于菜单项

        private void 关于ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            //【关于对话框】
            AboutBox aboutbox = new AboutBox();
            aboutbox.ShowDialog();      // 模态
        }
#endregion

#region  状态栏菜单 : CheckedChanged 事件
        /// <summary> 根据状态栏ToolStripMenuItem前面的【√】勾选状态, 设置状态栏控件: statusStrip1的显示状态
        ///         1. 处于勾选状态:  显示 statusStrip1 (statusStrip1.Visible = true;)
        ///         2. 处于未勾选状态:  隐藏  statusStrip1 (statusStrip1.Visible = false;)   
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void 状态栏ToolStripMenuItem_CheckedChanged(object sender, EventArgs e)
        {
            // 状态栏ToolStripMenuItem.Checked时, 返回true, 用于设置statusStrip1的Visible状态
            statusStrip1.Visible = 状态栏ToolStripMenuItem.Checked;
        }
#endregion

#region 工具栏菜单

        /// <summary> 根据工具栏ToolStripMenuItem前面的【√】勾选状态, , 设置状态栏控件: toolStrip1的显示状态
        ///         1. 处于勾选状态:  显示 toolStrip1 (toolStrip1.Visible = true;)
        ///         2. 处于未勾选状态:  隐藏  toolStrip1 (toolStrip1.Visible = false;)
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void 工具栏ToolStripMenuItem_CheckStateChanged(object sender, EventArgs e)
        {
            // 工具栏ToolStripMenuItem.Checked时, 返回true, 用于设置statusStrip1的Visible状态
            toolStrip1.Visible = 工具栏ToolStripMenuItem.Checked;
        }

#endregion

        private void contextMenuStrip2_Opening(object sender, CancelEventArgs e)
        {
            // 判断listBox1当前选中状态:  未选中 -1 
            if ( -1 == listBox1.SelectedIndex )
            {
                // 不显示上下文菜单(弹出菜单)
                //e.Cancel = true;

                // 禁用上下文菜单
                添加ToolStripMenuItem1.Enabled = false;
                编辑ToolStripMenuItem1.Enabled = false;
                删除ToolStripMenuItem1.Enabled = false;

            }
            else
            {
                添加ToolStripMenuItem1.Enabled = true;
                编辑ToolStripMenuItem1.Enabled = true;
                删除ToolStripMenuItem1.Enabled = true;
            }
        }

        private void 删除ToolStripMenuItem1_Click(object sender, EventArgs e)
        {
            string steel = "是否删除: " + listBox1.SelectedItem.ToString();
            if (DialogResult.Yes == MessageBox.Show(steel,"提示: ",MessageBoxButtons.YesNo))
            {
                listBox1.Items.RemoveAt(listBox1.SelectedIndex);
            }
        }
    }
}