我用c#打开一个excel，加了一个commandbar，按这个加的commandbar开启一个winform窗口，拖动这个窗口出现重影，一直找不到原因，打开按按钮就开一个excel，上面加了一个工具列，点工具，就出来winform窗口，拖动，重影

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;
using Excel = Microsoft.Office.Interop.Excel;
using Office = Microsoft.Office.Core;
using System.Reflection;
using Microsoft.VisualStudio.Tools.Applications.Runtime;

namespace 测试工具列
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private Office.CommandBar SaverToolBar;
        private Office.CommandBarButton StartButton;
        private Office.CommandBarButton SettingButton;
        private Office.CommandBarButton EnableButton;
        private Office.CommandBarComboBox SaverComboBox;
        private string SaverKey;
        private void button1_Click(object sender, EventArgs e)
        {

            Excel.Application app1 = new Excel.Application();
            app1.Visible = true;
            app1.ScreenUpdating = false;
            app1.DisplayAlerts = false;
            try
            {

                Excel.Workbook book1 = app1.Workbooks.Add(Type.Missing);

                //添加工具栏
                SaverToolBar = app1.CommandBars.Add("ExcelSaverToolbar", 1, Type.Missing, true);
                SaverToolBar.Visible = true;
                //添加工具栏按钮

                SettingButton = (Office.CommandBarButton)SaverToolBar.Controls.Add(Office.MsoControlType.msoControlButton, Type.Missing, Type.Missing, Type.Missing, true);
                SettingButton.Style = Office.MsoButtonStyle.msoButtonIconAndCaption;
                SettingButton.Caption = "设置保护密码";
                //CzExcel.CzOfficeResources.SetIcon(SettingButton, Globals.Sheet1.imageList1.Images[1]);
                
                SettingButton.Click += new Office._CommandBarButtonEvents_ClickEventHandler(SettingButton_Click);
                //app1.ScreenUpdating = true;
                //app1.Hwnd();
                //MessageBox.Show(app1.ScreenUpdating.ToString());
            }
            catch (Exception exp)
            {
                MessageBox.Show("程序初始化时发生错误：" + exp.Message, "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            finally
            {
                app1.ScreenUpdating = true;
            }
            
          
        }

        private void SettingButton_Click(Office.CommandBarButton Ctrl, ref bool CancelDefault)
        {
          
            
             
        
           
            Form2 frm = new Form2();
             frm.ShowDialog();
            //if (frm.ShowDialog() == DialogResult.OK)
            //    SaverKey = frm.Key;
        }

           }
}