How to programmatically restart windows explorer process

Question

I'm working on a windows shell extension, and unfortunately, when making changes to the DLL, I must restart windows explorer (since it keeps the DLL in memory).

I found this program from Dino Esposito, but it doesn't work for me.

void SHShellRestart(void)
{
    HWND hwnd;
    hwnd = FindWindow("Progman", NULL );
    PostMessage(hwnd, WM_QUIT, 0, 0 );
    ShellExecute(NULL, NULL, "explorer.exe", NULL, NULL, SW_SHOW );
    return;
}

Does any one have something they can share to do this?

P.S. I realize that I can go to task manager and kill the explorer process, but I just want to do it the lazy way. Besides, this enables automation.

P.P.S I am using .NET for the development, but the shell restart functionality could be in C, C++ or a .NET language. It will simply be a small stand-alone executable.

Answer 1

After parsing some of the earlier answers and doing a bit of research, I've created a little complete example in C#. This closes the explorer shell then waits for it to completely shut down and restarts it. Hope this helps, there's a lot of interesting info in this thread.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.Threading;

namespace RestartExplorer
{
class Program
{
    [DllImport("user32.dll", SetLastError = true)]
    static extern bool PostMessage(IntPtr hWnd, [MarshalAs(UnmanagedType.U4)] uint Msg, IntPtr wParam, IntPtr lParam);

    [DllImport("user32.dll", SetLastError = true)]
    static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

    const int WM_USER = 0x0400; //http://msdn.microsoft.com/en-us/library/windows/desktop/ms644931(v=vs.85).aspx

    static void Main(string[] args)
    {
        try
        {
            var ptr = FindWindow("Shell_TrayWnd", null);
            Console.WriteLine("INIT PTR: {0}", ptr.ToInt32());
            PostMessage(ptr, WM_USER + 436, (IntPtr)0, (IntPtr)0);

            do
            {
                ptr = FindWindow("Shell_TrayWnd", null);
                Console.WriteLine("PTR: {0}", ptr.ToInt32());

                if (ptr.ToInt32() == 0)
                {
                    Console.WriteLine("Success. Breaking out of loop.");
                    break;
                }

                Thread.Sleep(1000);
            } while (true);
        }
        catch (Exception ex)
        {
            Console.WriteLine("{0} {1}", ex.Message, ex.StackTrace);
        }
        Console.WriteLine("Restarting the shell.");
        string explorer = string.Format("{0}\\{1}", Environment.GetEnvironmentVariable("WINDIR"), "explorer.exe");
        Process process = new Process();           
        process.StartInfo.FileName = explorer;
        process.StartInfo.UseShellExecute = true;
        process.Start();

        Console.ReadLine();

    }
}
}