Sending Keystrokes to another Application in C#

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace SendKeys
{
    class NativeWin32
    {
        public const int WM_SYSCOMMAND = 0x0112;
        public const int SC_CLOSE = 0xF060;

        [DllImport("user32.dll")]
        public static extern int FindWindow(
            string lpClassName, // class name 
            string lpWindowName // window name 
        );

        [DllImport("user32.dll")]
        public static extern int SendMessage(
            int hWnd, // handle to destination window 
            uint Msg, // message 
            int wParam, // first message parameter 
            int lParam // second message parameter 
        );

        [DllImport("user32.dll")]
        public static extern int SetForegroundWindow(
            int hWnd // handle to window
            );

        private const int GWL_EXSTYLE = (-20);
        private const int WS_EX_TOOLWINDOW = 0x80;
        private const int WS_EX_APPWINDOW = 0x40000;
              
        public const int GW_HWNDFIRST = 0;
        public const int GW_HWNDLAST  = 1;
        public const int GW_HWNDNEXT  = 2;
        public const int GW_HWNDPREV  = 3;
        public const int GW_OWNER     = 4;
        public const int GW_CHILD     = 5;

        public delegate int EnumWindowsProcDelegate(int hWnd, int lParam);

        [DllImport("user32")]
        public static extern int EnumWindows(EnumWindowsProcDelegate lpEnumFunc, int lParam);

        [DllImport("User32.Dll")]
        public static extern void GetWindowText(int h, StringBuilder s, int nMaxCount);

        [DllImport("user32", EntryPoint = "GetWindowLongA")]
        public static extern int GetWindowLongPtr(int hwnd, int nIndex);

        [DllImport("user32")]
        public static extern int GetParent(int hwnd);

        [DllImport("user32")]
        public static extern int GetWindow(int hwnd, int wCmd);

        [DllImport("user32")]
        public static extern int IsWindowVisible(int hwnd);

        [DllImport("user32")]
        public static extern int GetDesktopWindow();
    }
}