Public Class ClassMain
    Public Shared Sub Main()
        Application.Run(New Form1)
    End Sub
End Class

Public Class Person
    Inherits Object
    Public Delegate Sub DelegatePersonHasChange(ByVal sender As Object, ByVal e _
      As PersonHasChangeEventArgs)
    Public EventHandlerPersonHasChange As DelegatePersonHasChange
    Private _Nachname As String
    Private Sub RaisePersonHasChangeEvent()
        EventHandlerPersonHasChange.Invoke(Me, New PersonHasChangeEventArgs( _
          Me._Nachname))
    End Sub
    Public Sub New(ByVal Nachname As String)
        Me._Nachname = Nachname
    End Sub
    Public Property Nachname() As String
        Get
            Return _Nachname
        End Get
        Set(ByVal Value As String)
            _Nachname = Value
            RaisePersonHasChangeEvent()
        End Set
    End Property
    Private Shared _Person As Person
    Public Shared Function GetInstance() As Person
        If _Person Is Nothing Then
            _Person = New Person(Nothing)
        End If
        Return _Person
    End Function
End Class
Public Class PersonHasChangeEventArgs
    Inherits EventArgs
    Private _Nachname As String
    Public Sub New(ByVal Nachname As String)
        Me._Nachname = Nachname
    End Sub
    Public ReadOnly Property Nachname() As String
        Get
            Return _Nachname
        End Get
    End Property
    Public Overrides Function ToString() As String
        Return Me.Nachname
    End Function
End Class

Public Class Form1
    Inherits System.Windows.Forms.Form
#Region " Vom Windows Form Designer generierter Code "
#End Region
    Dim myPerson As Person
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        myPerson = Person.GetInstance()
        myPerson.EventHandlerPersonHasChange = New _
          Person.DelegatePersonHasChange(AddressOf PersonHasChangeEventHandler)
        Dim f2 As New Form2
        f2.Show()
    End Sub
    Private Sub PersonHasChangeEventHandler(ByVal sender As Object, ByVal e As _
      PersonHasChangeEventArgs)
        Debug.WriteLine("Daten wurden verändert: " + e.ToString)
    End Sub
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        myPerson.Nachname = "Meier"
    End Sub
End Class

Public Class Form2
    Inherits System.Windows.Forms.Form
#Region " Vom Windows Form Designer generierter Code "
#End Region
    Dim myPerson As Person
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        myPerson = Person.GetInstance() '// << nur eine Instanz verwenden, wg. 
        ' "Global"
        myPerson.EventHandlerPersonHasChange = New _
          Person.DelegatePersonHasChange(AddressOf PersonHasChangeEventHandler)
    End Sub
    Private Sub PersonHasChangeEventHandler(ByVal sender As Object, ByVal e As _
      PersonHasChangeEventArgs)
        Debug.WriteLine("Daten wurden verändert: " + e.ToString)
    End Sub
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        myPerson.Nachname = "Lustig"
    End Sub
End Class