Private Const EM_SETTABSTOPS As UInt32 = &HCB
 
    <DllImport("User32.dll")> _
    Shared Function SendMessage(ByVal hWnd As IntPtr, _
    ByVal msg As Integer, ByVal wParam As Integer, _
    ByVal lParam() As Integer) As IntPtr
    End Function
 
    <SecurityPermission(SecurityAction.LinkDemand, _
      Flags:=SecurityPermissionFlag.UnmanagedCode)> _
    Sub SetTabLength(ByVal control As Control, ByVal distance As Integer)
        If TypeOf control Is TextBox Or TypeOf control Is RichTextBox Then
            ' du musst die anzahl der zeichen mal 4 nehmen um die displayunits 
            ' zu kriegen.
            distance = CType(distance * 4, Integer)
            SendMessage(control.Handle, EM_SETTABSTOPS, 1, New Integer() _
              {distance})
        End If
    End Sub