Clean Install Windows 10 from Windows 8 (resolve activation problem)

1. From within Windows 8, update to Windows 10
2. Activate Windows 10
3. Create Installation Media (Thumbdrive)
4. Boot from Installation Media, format disk and install Windows 10 again
5. If have problem activating - type "slmgr.vbs /ato" (without quotes)  from command prompt (as administrator)

How to dramatically increase the performance of WinForm DataGridView?

Add this extension method:

public static void DoubleBuffered(this DataGridView dgv, bool setting)
{
    Type dgvType = dgv.GetType();
    PropertyInfo pi = dgvType.GetProperty("DoubleBuffered",
          BindingFlags.Instance | BindingFlags.NonPublic);
    pi.SetValue(dgv, setting, null);
}

How to make an eventhandler run asynchronously?

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Threading;
using System.Diagnostics;
namespace WindowsFormsApplication6
{
    public partial class Form1 : Form
    {
        private Thread SecondaryThread;

        public Form1()
        {
            InitializeComponent();

            OperationFinished += callback1;
            OperationFinished += callback2;
            OperationFinished += callback3;
        }
       
        private void Form1_Load(object sender, EventArgs e)
        {
            SecondaryThread = new Thread(new ThreadStart(SecondaryThreadMethod));
            SecondaryThread.Start();
        }

         private void SecondaryThreadMethod()
         {
            Stopwatch sw = new Stopwatch();
            sw.Restart();

            OnOperationFinished(new MessageEventArg("test1"));
            OnOperationFinished(new MessageEventArg("test2"));
            OnOperationFinished(new MessageEventArg("test3"));

            OnOperationFinished(new MessageEventArg("test4"));
            OnOperationFinished(new MessageEventArg("test5"));
            OnOperationFinished(new MessageEventArg("test6"));

            OnOperationFinished(new MessageEventArg("test7"));
            OnOperationFinished(new MessageEventArg("test8"));
            OnOperationFinished(new MessageEventArg("test9"));
            //This is where the program waits for whatever operations take
                 //place when OperationFinished is triggered.

            sw.Stop();

            Invoke((MethodInvoker)delegate
            {
                richTextBox1.Text += "Time taken (ms): " + sw.ElapsedMilliseconds + "\n";
            });
         }

        void callback1(object sender, MessageEventArg e)
        {
            Thread.Sleep(2000);
            Invoke((MethodInvoker)delegate
            {
                richTextBox1.Text += e.Message + "\n";
            });
        }
        void callback2(object sender, MessageEventArg e)
        {
            Thread.Sleep(2000);
            Invoke((MethodInvoker)delegate
            {
                richTextBox1.Text += e.Message + "\n";
            });
        }

        void callback3(object sender, MessageEventArg e)
        {
            Thread.Sleep(2000);
            Invoke((MethodInvoker)delegate
            {
                richTextBox1.Text += e.Message + "\n";
            });
        }

        public event EventHandler<MessageEventArg> OperationFinished;

        protected void OnOperationFinished(MessageEventArg e)
        {
            //##### Method1 - Event raised on the same thread #####
            //EventHandler<MessageEventArg> handler = OperationFinished;

            //if (handler != null)
            //{
            //    handler(this, e);
            //}

            //##### Method2 - Event raised on (the same) separate thread for all listener #####
            EventHandler<MessageEventArg> handler = OperationFinished;

            if (handler != null)
            {
                Task.Factory.StartNew(() => handler(this, e));
            }

            //##### Method3 - Event raised on different threads for each listener #####
            //if (OperationFinished != null)
            //{
            //    foreach (EventHandler<MessageEventArg> handler in OperationFinished.GetInvocationList())
            //    {
            //        Task.Factory.FromAsync((asyncCallback, @object) => handler.BeginInvoke(this, e, asyncCallback, @object), handler.EndInvoke, null);
            //    }
            //}
        }
    }

    public class MessageEventArg : EventArgs
    {
        public string Message { get; set; }

        public MessageEventArg(string message)
        {
            this.Message = message;
        }
    }
}