find the parent window of an item in a actipro toolwindow

<ribbon:RibbonWindow x:Class="MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:docking="http://schemas.actiprosoftware.com/winfx/xaml/docking"
    xmlns:local="clr-namespace:WpfApplication1"
    xmlns:ribbon="http://schemas.actiprosoftware.com/winfx/xaml/ribbon"
    Title="MainWindow" Height="350" Width="525">
    <Grid>
    <DockPanel >
      <docking:ToolWindowContainer>
        <docking:ToolWindow>
          <Grid>
            <Button Width="73" Height="23" Name="rr">click</Button>
          </Grid>
        </docking:ToolWindow>
      </docking:ToolWindowContainer>
    </DockPanel>

  </Grid>
</ribbon:RibbonWindow>

  Private Sub rr_Click(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles rr.Click
    Dim Owner As Window = FindParentWindow(Me)
  End Sub



  Public Shared Function FindParentWindow(ByVal CurrentElement As Object) As DependencyObject
    On Error Resume Next
    Dim P As Object = Nothing
    If TypeOf CurrentElement.parent Is ContentControl Then
      P = CurrentElement.parent
    Else
      P = VisualTreeHelper.GetParent(CurrentElement)
    End If
    If IsNothing(P) Then
      Return Nothing 'not found, end of tree
    Else
      If P.GetType Is GetType(Window) OrElse P.GetType Is GetType(RibbonWindow) OrElse P.GetType.BaseType Is GetType(Window) OrElse P.GetType.IsSubclassOf(GetType(Window)) Then 'found a visual of the desired type!
        Return P
      Else
        Return FindParentWindow(P)
      End If
    End If
  End Function