winform批改菜单背景色后不显示，依旧是默认背景色，求解答

winform修改菜单背景色后不显示，依旧是默认背景色，求解答
如图所示，我明明修改了背景色，还是没有发生改变，求解答 winform 背景色
[解决办法]

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;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            foreach (ToolStripItem item in menuStrip1.Items)
            {
                EnumChildMenu(item);
            }
        }

        private void EnumChildMenu(ToolStripItem tsi)
        {
            OnFind(tsi);
            if (tsi is ToolStripMenuItem)
            {
                ToolStripMenuItem tsmi = tsi as ToolStripMenuItem;
                foreach (ToolStripItem item in tsmi.DropDownItems)
                {
                    EnumChildMenu(item);
                }
            }
        }

        private void OnFind(ToolStripItem tsi)
        {
            tsi.BackColor = Color.Blue;
        }
    }
}