1、添加用於啟動的類Program.cs，需要一個靜態的Main函數入口。

using System;
using System.Windows;
using System.Windows.Controls;

public class Program
    {
        private static Application _MainApplication;

        internal static Application MainApplication
        {
            get { return _MainApplication ?? (_MainApplication = new Application()); }
        }

        [STAThread]
        public static void Main(string[] args)
        {
            var MainWin = new Window();
            var FollowWin = new Window();
            //拉姆達表達式
            MainWin.Loaded +=
                (s, e) =>
                {
                    FollowWin.WindowStartupLocation = WindowStartupLocation.Manual;
                    FollowWin.Left = MainWin.Left + MainWin.Width;
                    FollowWin.Top = MainWin.Top;
                    FollowWin.Show();
                };
 

            //當窗口位置更改時發生
            MainWin.LocationChanged +=
                (s, e) =>
                {
                    FollowWin.Left = MainWin.Left + MainWin.Width;
                    FollowWin.Top = MainWin.Top;
                };
            MainApplication.ShutdownMode = ShutdownMode.OnExplicitShutdown;
            MainApplication.Run(touch);
        }
    }
 

2、設置類庫項目的輸出類型為“Windows應用程序”：

3、設置啟動對象為第一步中創建的Program

4、運行即可。

WPF 設置類庫項目為啟動項，設置窗體跟隨。