VSTO中的自定義功能區和自定義任務窗格需要用到各種名稱空間、新增所需檔案，才能實現。後來我發現可以把所有程式碼都寫在ThisAddin.cs這個預設檔案中。

大家可以在Visual Studio中建立一個外接程式專案，然後把ThisAddin.cs中的程式碼整體替換為下面我貼的這個程式碼。然後啟動除錯，就可以看到自定義功能區和任務窗格了。

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Xml.Linq;
 
 6 using Excel = Microsoft.Office.Interop.Excel;
 7 using Office = Microsoft.Office.Core;
 8 using Microsoft.Office.Tools.Excel;
 9 
10 namespace ExcelAddInTemplate_CS
11 {
12     public partial class ThisAddIn
13     {
14         private void ThisAddIn_Startup(object sender, System.EventArgs e)
 
15         {
16             Module1.CreateCTP();
17         }
18 
19         private void ThisAddIn_Shutdown(object sender, System.EventArgs e)
20         {
21             Module1.DisposeCTP();
22         }
23         protected override Office.IRibbonExtensibility CreateRibbonExtensibilityObject()
 
24         {
25             return new Ribbon1();
26         }
27         #region VSTO generated code
28 
29         /// <summary>
30         /// Required method for Designer support - do not modify
31         /// the contents of this method with the code editor.
32         /// </summary>
33         private void InternalStartup()
34         {
35             this.Startup += new System.EventHandler(ThisAddIn_Startup);
36             this.Shutdown += new System.EventHandler(ThisAddIn_Shutdown);
37         }
38         
39         #endregion
40     }
41     [System.Runtime.InteropServices.ComVisible(true)]
42     public class Ribbon1:Microsoft.Office.Core.IRibbonExtensibility
43     {
44         public Office.IRibbonUI R;
45         string Office.IRibbonExtensibility.GetCustomUI(string RibbonID)
46         {
47             string xml= @"<customUI xmlns='http://schemas.microsoft.com/office/2009/07/customui' onLoad='OnLoad'>
48     <ribbon startFromScratch='false'>
49         <tabs>
50             <tab id='Tab1' label='RibbonXmlEditor'>
51                 <group id='Group1' label='Author:ryueifu'>
52                     <button id='Button1' label='CTP' imageMso='C' onAction='Button1_Click'/>
53                     <button id='Button2' label='UnLoad' imageMso='U' onAction='Button2_Click'/>
54                 </group>
55             </tab>
56         </tabs>
57     </ribbon>
58 </customUI>";
59             return xml;
60         }
61         public void OnLoad(Office.IRibbonUI ribbon)
62         {
63             R = ribbon;
64             R.ActivateTab(ControlID: "Tab1");
65         }
66         public void Button1_Click(Office.IRibbonControl control)
67         {
68             Module1.ctp.Visible = !Module1.ctp.Visible;
69         }
70         public void Button2_Click(Office.IRibbonControl control)
71         {
72             Office.COMAddIn ThisCOM = Globals.ThisAddIn.Application.COMAddIns.Item("ExcelAddInTemplate_CS");
73             ThisCOM.Connect = false;
74         }
75 
76     }
77     public static class Module1
78     {
79         public static System.Windows.Forms.UserControl uc;
80         public static Microsoft.Office.Tools.CustomTaskPane ctp;
81         public static void CreateCTP()
82         {
83             uc = new System.Windows.Forms.UserControl();
84             ctp = Globals.ThisAddIn.CustomTaskPanes.Add(control: uc, title: "CTP");
85             ctp.DockPosition = Office.MsoCTPDockPosition.msoCTPDockPositionRight;
86             ctp.Visible = true;
87         }
88         public static void DisposeCTP()
89         {
90             ctp.Dispose();
91         }
92     }
93 }