How to detect a mouse down using WebView2 in C# and then hiding the open MenuStrip?

Question

In a form I have a MenuStrip and a Webview2 component.
The MenuStrip does not close when you click on the Webview2 component.
I am unable to detect a mouse click using WebView2 in C# and so I cannot close the MenuStrip called menuStrip1.
Can I just simple use the event webView21_MouseDown ?
I have tried all kinds of solutions found on the internet but I cannot get it to work.
What am I missing?

using System;  
using System.Windows.Forms;  
using Microsoft.Web.WebView2.Core;  

namespace TestWebView2  
{  
    public partial class Form1 : Form  
    {  
        public Form1()  
        {  
            InitializeComponent();  
            InitializeWebview2();  
        }  

        private void Form1_Load(object sender, EventArgs e)  
        {  
        }  

        private async void InitializeWebview2()
        {
            await webView21.EnsureCoreWebView2Async(null);
        }

        private void webView21_MouseClick(object sender, MouseEventArgs e)
        {
            MessageBox.Show("it does not work");
        }

        private void webView21_MouseDown(object sender, MouseEventArgs e)
        {
            MessageBox.Show("it does not work");
        }
    }
}

The MenuStrip does not close when you click on the Webview2 component.