C#

protected override void WndProc(ref Message m)<br />
			{<br />
                                base.WndProc(ref m);<br />
				if (m.Msg == WM_NOTIFY)<br />
				{<br />
					NMHDR hdr = (NMHDR)Marshal.PtrToStructure(m.LParam, typeof(NMHDR));<br />
					if (hdr.hwndFrom == hWndHeader &&<br />
						(hdr.code == HDN_ITEMCHANGEDA || hdr.code == HDN_ITEMCHANGEDW))<br />
					{<br />
                                                       m.Result = new IntPtr(0);// I do this<br />
						<br />
                                                        NMHEADER header = (NMHEADER)<br />
							Marshal.PtrToStructure(m.LParam, typeof(NMHEADER));<br />
<br />
						int index = header.iItem;<br />
						if (index >= 0 && index < Columns.Count)<br />
						{<br />
							ColumnHeader col = Columns[index];<br />
							OnColumnHeaderChanged(new ColumnHeaderChangedEventArgs(col));<br />
						}<br />
					}<br />
				}<br />
			}

<br />
			protected override void WndProc(ref Message m)<br />
			{<br />
				m.Result = new IntPtr(0);<br />
				base.WndProc(ref m);<br />
				if (m.Msg == WM_NOTIFY)<br />
				{<br />

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

[assembly: AssemblyVersion("1.0.*")]
[assembly: AssemblyKeyFile(@"C:\Proplanner.NET\KeyFile.snk")]

public class Test : Form
{
  static void Main(string[] args)
  {
    bool b = true;
    if (args.Length > 0)
    {
      try
      {
        b = bool.Parse(args[0]);
      }
      catch {}
    }
    
    Application.Run(new Test(b));
  }

  public Test(bool allowResizing)
  {
    SuspendLayout();

    Text = "MyListView Test";

    MyListView lv = new MyListView();
    Controls.Add(lv);
    lv.Dock = DockStyle.Fill;
    lv.View = View.Details;
    lv.AllowResizing = allowResizing;
    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;
  private bool allowResizing = true;
  
  public bool AllowResizing
  {
    get { return allowResizing; }
    set { allowResizing = value; }
  }

  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)
      {
        if (hdr.code == HDN_ITEMCHANGINGA ||
          hdr.code == HDN_ITEMCHANGINGW)
        {
          if (allowResizing) m.Result = FALSE;
          else m.Result = TRUE;
        }
        else if (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_ITEMCHANGINGA = -300;
  private const int HDN_ITEMCHANGINGW = -320;
  private const int HDN_ITEMCHANGEDA = -301;
  private const int HDN_ITEMCHANGEDW = -321;
  private const int LVM_GETHEADER = 4127;
  private static readonly IntPtr FALSE = new IntPtr(0);
  private static readonly IntPtr TRUE = new IntPtr(1);

  [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; }
  }
}