C#

/// Code on the first form.

private void button1_Click(object sender, System.EventArgs e)
{
Form2 form2 = new Form2(this);
form2.Show();
}


/// Code on the second form.

Form _form1 = null;
public Form2(Form form1)
{
    _form1 = form1;
}
private void button1_Click(object sender, System.EventArgs e)
{
label1.Text = _form1.textBox1.Text;
} 

DateTime ConvertFromString(string s)
{
    if(s == "")
        return DateTime.MinValue;
    else
        // Remember exception handling here
        return Convert.ToDateTime(s);
}

public class MyEventArgs : EventArgs
{
  String _myString = String.Empty;

  public MyEventArgs(String aString)
  {
    _myString = aString;
  }

  public string MyString
  {
    get { return _myString; }
    set { _myString = value; }
  }
}

protected override void OnDoubleClick(EventArgs e)
{ 
  MyEventArgs args = new MyEventArgs("MyEventArgs");
  base.OnDoubleClick(args);
}

private void MyControlDoubleClicked(object sender, EventArgs e)
{
  MyEventArgs args = (MyEventArgs)e;
  MessageBox.Show(args.MyString);
}