鼠标移到控件上显示，移出控件消失

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

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

        private void Form1_Load(object sender, EventArgs e)
        {          
            button1.Visible = false;
        }

        private void Form1_MouseMove(object sender, MouseEventArgs e)
        {         
             Point point= this.PointToScreen(new Point(e.X, e.Y));
             Rectangle rc = this.button1.RectangleToScreen(this.button1.ClientRectangle);
             if (rc.Contains(point))
             {
                 button1.Visible = true;
             }
             else
             {
                 button1.Visible = false;
             }           
        }                 
    }
}