C#

HttpWebRequest request = (HttpWebRequest)
  WebRequest.Create("http://www.umc.ua/misc/sendsms.php");
request.Method = "POST"
request.ContentType = "application/x-www-form-urlencoded";
string postData =
  "network1=UMC&Phone1=5918658&Message=HellofromCSharp&sender_name=sn";
byte[] buffer = Encoding.ASCII.GetBytes(postData);
request.ContentLength = buffer.Length;
Stream s = request.GetRequestStream();
s.Write(buffer, 0, buffer.Length);
s.Flush();
s.Close();
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
// ...

using System;
using System.Drawing;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Windows.Forms;

[assembly: AssemblyVersion("1.0.*")]
[assembly: AssemblyKeyFile(@"C:\Path\To\KeyFile.snk")] // sn.exe -k KeyFile.snk

namespace Test
{
  [Guid("0eea66bf-21bf-4c8c-8678-ad58106343a7")]
  [InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
  public interface ITest
  {
    [DispId(0)]
    DialogResult ShowDialog();
  }

  [ClassInterface(ClassInterfaceType.None)]
  [Guid("861e1098-7705-4686-945e-236a0ef439ef")]
  [ProgId("Test.Test")]
  public class Test : Form, ITest
  {
    static void Main()
    {
      Application.Run(new Test());
    }

    public Test()
    {
      SuspendLayout();

      Text = "Out-of-Proc Server Test";

      Label lbl = new Label();
      Controls.Add(lbl);
      lbl.Location = new Point(8, 8);
      lbl.Text = "Hello, world!";

      ResumeLayout();
    }
  }
}

regasm.exe /tlb /codebase Test.exe

var test = new ActiveXObject("Test.Test");
test.ShowDialog();

csc /t:exe Test.cs

using System;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;

public class Test : Form
{
  static void Main()
  {
    Application.Run(new Test());
  }

  public Test()
  {
    SuspendLayout();

    Text = "MyListView Test";

    MyListView lv = new MyListView();
    Controls.Add(lv);
    lv.Dock = DockStyle.Fill;
    lv.View = View.Details;
    lv.ColumnHeaderChanged += new ColumnHeaderChangedEventHandler(
      lv_ColumnHeaderChanged);

    ColumnHeader col1 = new ColumnHeader();
    col1.Text = "One";

    ColumnHeader col2 = new ColumnHeader();
    col2.Text = "Two";
    
    lv.Columns.Add(col1);
    lv.Columns.Add(col2);

    ResumeLayout();
  }

  private void lv_ColumnHeaderChanged(object sender,
    ColumnHeaderChangedEventArgs e)
  {
    Console.WriteLine("Column {0} changed: new width = {1}",
      e.ColumnHeader.Text, e.ColumnHeader.Width);
  }
}

public class MyListView : ListView
{
  private IntPtr hWndHeader;

  protected override void OnHandleCreated(EventArgs e)
  {
    base.OnHandleCreated(e);
    hWndHeader = SendMessage(Handle, LVM_GETHEADER, 0, 0);
  }
  
  protected override void WndProc(ref Message m)
  {
    base.WndProc(ref m);
    if (m.Msg == WM_NOTIFY)
    {
      NMHDR hdr = (NMHDR)Marshal.PtrToStructure(m.LParam, typeof(NMHDR));
      if (hdr.hwndFrom == hWndHeader &&
        (hdr.code == HDN_ITEMCHANGEDA || hdr.code == HDN_ITEMCHANGEDW))
      {
        NMHEADER header = (NMHEADER)
          Marshal.PtrToStructure(m.LParam, typeof(NMHEADER));

        int index = header.iItem;
        if (index >= 0 && index < Columns.Count)
        {
          ColumnHeader col = Columns[index];
          OnColumnHeaderChanged(new ColumnHeaderChangedEventArgs(col));
        }
      }
    }
  }

  public event ColumnHeaderChangedEventHandler ColumnHeaderChanged;

  protected virtual void OnColumnHeaderChanged(ColumnHeaderChangedEventArgs e)
  {
    if (ColumnHeaderChanged != null)
      ColumnHeaderChanged(this, e);
  }

  private const int WM_NOTIFY = 78;
  private const int HDN_ITEMCHANGEDA = -301;
  private const int HDN_ITEMCHANGEDW = -321;
  private const int LVM_GETHEADER = 4127;

  [StructLayout(LayoutKind.Sequential)]
  public class NMHDR
  {
    public IntPtr hwndFrom;
    [MarshalAs(UnmanagedType.U4)] public int idFrom;
    [MarshalAs(UnmanagedType.U4)] public int code;
  }

  [StructLayout(LayoutKind.Sequential)]
  public class NMHEADER
  {
    public IntPtr hwndFrom;
    [MarshalAs(UnmanagedType.U4)] public int idFrom;
    [MarshalAs(UnmanagedType.U4)] public int code;
    public int iItem;
    public int iButton;
    public IntPtr pitem;
  }

  [DllImport("user32.dll")]
  private static extern IntPtr SendMessage(IntPtr hWnd, int msg,
    int wParam, int lParam);
}

public delegate void ColumnHeaderChangedEventHandler(object sender,
  ColumnHeaderChangedEventArgs e);

public class ColumnHeaderChangedEventArgs : EventArgs
{
  private ColumnHeader columnHeader;

  public ColumnHeaderChangedEventArgs(ColumnHeader header)
  {
    columnHeader = header;
  }

  public ColumnHeader ColumnHeader
  {
    get { return columnHeader; }
  }
}