Private filter As ScrollPanelMessageFilter
 
   Private Sub Panel1_Scroll(ByVal sender As System.Object, ByVal e As _
     System.Windows.Forms.ScrollEventArgs) Handles Panel1.Scroll
      lblScrollValue.Text = e.NewValue.ToString
   End Sub
 
   Private Sub btnScroll_Click(ByVal sender As System.Object, ByVal e As _
     System.EventArgs) Handles btnScroll.Click
      ScrollToBottom()
   End Sub
 
   Public Sub ScrollToBottom()
      Panel1.VerticalScroll.Value = Panel1.DisplayRectangle.Height - _
        Panel1.ClientRectangle.Height
   End Sub
 
   Private Sub ViewerList_MouseEnter(ByVal sender As System.Object, ByVal e As _
     System.EventArgs) Handles MyBase.MouseEnter, Panel1.MouseEnter
      filter = New ScrollPanelMessageFilter(Me.Panel1)
      Application.AddMessageFilter(filter)
   End Sub
 
   Private Sub ViewerList_MouseLeave(ByVal sender As System.Object, ByVal e As _
     System.EventArgs) Handles MyBase.MouseLeave
      Application.RemoveMessageFilter(filter)
   End Sub
 
   Private Class ScrollPanelMessageFilter
      Implements IMessageFilter
 
      Private Panel As Panel
      Private panelHasFocus As Boolean = False
 
      Const WM_MOUSEWHEEL As Integer = &H20A
      Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal _
        hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, ByVal _
        lParam As Integer) As Integer
 
      Public Sub New(ByVal Panel As Panel)
         Me.Panel = Panel
         AddFocusEvents(Panel)
      End Sub
 
      Private Sub AddFocusEvents(ByVal parentControl As Control)
         ' Für jedes Control die entsprechenden Events hinzufügen
         For Each ctrl As Control In parentControl.Controls
            If ctrl.Controls.Count = 0 Then
               ' Events hinzufügen
               AddHandler ctrl.GotFocus, AddressOf control_GotFocus
               AddHandler ctrl.LostFocus, AddressOf control_LostFocus
            Else
               ' Methode rekursiv ausführen, wenn Sub-Control Controls enthält
               AddFocusEvents(ctrl)
            End If
         Next
      End Sub
 
      Private Sub control_GotFocus(ByVal sender As Object, ByVal e As EventArgs)
         panelHasFocus = True
      End Sub
 
      Private Sub control_LostFocus(ByVal sender As Object, ByVal e As _
        EventArgs)
         panelHasFocus = False
      End Sub
 
      Public Function PreFilterMessage(ByRef m As System.Windows.Forms.Message) _
        As Boolean Implements _
        System.Windows.Forms.IMessageFilter.PreFilterMessage
         If m.Msg = WM_MOUSEWHEEL And Panel.CanFocus And Not panelHasFocus And _
         Panel.VerticalScroll.Visible Then
            Dim rect As Rectangle = Panel.RectangleToScreen( _
            Panel.ClientRectangle)
            Dim cursorPoint As New Point(Cursor.Position.X, Cursor.Position.Y)
 
            ' If-Abfrage, wenn Scrollen nur möglich sein soll, wenn der 
            ' Mauszeiger
            ' über dem Panel ist
 
            ' If (cursorPoint.X > rect.X And cursorPoint.X < rect.X + 
            ' rect.Width) And (cursorPoint.Y > rect.Y And cursorPoint.Y < 
            ' rect.Y + rect.Height) Then
            SendMessage(CInt(Panel.Handle), m.Msg, CInt(m.WParam), CInt( _
              m.LParam))
            Return True
            ' End If
         End If
 
         Return False
      End Function
   End Class