C#

public delegate void SentHandler(object sender, SentArgs e);
public class Example
{
  public event SentEventHandler Sent;
  protected virtual void OnSent(SentEventArgs e)
  {
    if (Sent != null)
      Sent(this, e);
  }
  public void Send(string message)
  {
    // ...
    OnSent(new SentEventArgs(message));
  }
}
public class SentEventArgs : EventArgs
{
  string message;
  public SentEventArgs(string message)
  {
    this.message = message;
  }
  public string Message
  {
    get { return message; }
  }
}

public class Test
{
  static void Main()
  {
    Test t = new Test();
    t.A();
    t.B();
    t = new Test2();
    t.A();
    t.B();
    ((Test2)t).A();
    ((Test2)t).B();
  }
  public void A()
  {
    Console.WriteLine("Test.A");
  }
  public virtual void B()
  {
    Console.WriteLine("Test.B");
  }
}
public class Test2 : Test
{
  public new A()
  {
    Console.WriteLine("Test2.A");
  }
  public override void B()
  {
    Console.WriteLine("Test2.B");
  }
}

Test.A
Test.B
Test.A
Test2.B
Test2.A
Test2.B

public override bool PreProcessMessage(ref System.Windows.Forms.Message msg)
{
  Keys keyCode=(Keys)(int)msg.WParam & Keys.KeyCode;
  if((msg.Msg==WM_KEYDOWN || msg.Msg==WM_KEYUP) &&  keyCode==Keys.Enter) 
  {
      msg.WParam=(System.IntPtr)0;
      // Do stuff here
        return true;
  }
}

protected override bool ProcessDialogKey(Keys keyData)
{
  if (keyData == Keys.Enter)
  {
    SendKeys.Send("{TAB}"); // Quick and dirty way
  }
  return false; // Continue processing the key(s)
}

<br />
// Create a formatter object<br />
IFormatter formatter = new BinaryFormatter();<br />
<br />
// Create a memoryStream<br />
MemoryStream ms = new MemoryStream();<br />
<br />
// Serialize the object (here of type MyNameSpace.MyTreeNode2) into the memory stream using the binary formatter<br />
formatter.Serialize(ms, draggedItem);<br />
<br />
// Put the byte array from the memory stream into a data object and specify the format <br />
// type to be of type "MyNameSpace.MyTreeNode2"<br />
DataObject dObj = new DataObject( "MyNamespace.MyTreeNode2", ms.GetBuffer() );<br />
selectedTreeView.DoDragDrop( dObj, DragDropEffects.All );<br />

<br />
// check the data member of drag event argument for the data we're willing to receive<br />
if ( e.Data.GetDataPresent("MyNamespace.MyTreeNode2") )<br />
{<br />
MyTreeNode2 data = null;<br />
IFormatter formatter = new BinaryFormatter();<br />
<br />
byte[] serializedBytes = (byte[])e.Data.GetData("MyNamespace.MyTreeNode2", false);<br />
MemoryStream ms = new MemoryStream( serializedBytes );<br />
data = (MyTreeNode2)formatter.Deserialize( ms );<br />
...<br />