WPFとVB.NET、ControlTemplateを使ったThumbを回転表示する時に回転させるのはどれがいいのか

'ThumbのTemplateを指定した時どれを回転させればドラッグ移動がうまくいくのか
'結果はThumb以外のどれかが良さそう
'Template中のCanvasかCanvasの中に入れたものになるけど
'Canvasがいいかなあってところ

Imports System.Windows.Controls.Primitives

Class MainWindow
    'Thumbの座標セット
    Private Sub SetLocate(obj As Object, p As Point)
        Canvas.SetLeft(obj, p.X)
        Canvas.SetTop(obj, p.Y)
    End Sub

    'Thumbの座標ゲット
    Private Function GetLocate(obf As Object) As Point
        Return New Point(Canvas.GetLeft(obf), Canvas.GetTop(obf))
    End Function

    'Thumbのマウスドラッグイベント用
    Private Sub ThumbDragDelta(sender As Object, e As DragDeltaEventArgs)
        Dim t As Thumb = DirectCast(sender, Thumb)
        Dim np As New Point(e.HorizontalChange, e.VerticalChange)
        np = np + GetLocate(t)
        Call SetLocate(t, np)
    End Sub

    '回転角度と拡大率を指定したTransformGroupを返す
    Private Function GetTransformGroup(angle As Double, scale As Double) As TransformGroup
        Dim tg As New TransformGroup
        tg.Children.Add(New RotateTransform(angle))
        tg.Children.Add(New ScaleTransform(scale, scale))
        Return tg
    End Function

    'Canvasを入れたTemplate付きのThumbを作成
    Private Function GetThumb() As Thumb
        Dim ct As New ControlTemplate
        ct.VisualTree = New FrameworkElementFactory(GetType(Canvas), "cc")

        Dim t As New Thumb
        t.Template = ct
        t.ApplyTemplate() 'Template再構成

        'Dim c As Canvas = t.Template.FindName("cc", t)
        'c.Background = Brushes.Transparent 'これをつけると透明部分でもドラッグ移動できる
        Return t
    End Function

    'Thumbを60度回転させて表示
    Private Sub AddThumbRotateThumb()
        Dim t As Thumb = GetThumb()
        Dim c As Canvas = t.Template.FindName("cc", t)
        Dim r As New Border With {
            .Background = Brushes.Cyan, .Width = 100, .Height = 100}
        Dim tb As New TextBlock With {.Text = "Thumbを60度回転"}
        t.Width = r.Width
        t.Height = r.Height
        c.Children.Add(r)
        c.Children.Add(tb)
        canvas1.Children.Add(t)
        SetLocate(t, New Point(50, 100))
        'Thumbを回転
        t.RenderTransform = GetTransformGroup(60, 1)
        t.RenderTransformOrigin = New Point(0.5, 0.5)
        AddHandler t.DragDelta, AddressOf ThumbDragDelta
    End Sub

    'Thumbの中のCanvasを60度回転させて表示
    Private Sub AddThumbRotateCanvas()
        Dim t As Thumb = GetThumb()
        Dim c As Canvas = t.Template.FindName("cc", t)
        Dim r As New Border With {
            .Background = Brushes.Cyan, .Width = 100, .Height = 100}
        Dim tb As New TextBlock With {
            .Text = "Thumbの中のCanvasを60度回転",
            .TextWrapping = TextWrapping.Wrap,
            .Width = r.Width}
        t.Width = r.Width
        t.Height = r.Height
        c.Children.Add(r)
        c.Children.Add(tb)
        canvas1.Children.Add(t)
        SetLocate(t, New Point(200, 100))
        Dim cc As Canvas = t.Template.FindName("cc", t)
        'Thumbの中のCanvasを回転
        cc.RenderTransform = GetTransformGroup(60, 1)
        cc.RenderTransformOrigin = New Point(0.5, 0.5)
        AddHandler t.DragDelta, AddressOf ThumbDragDelta
    End Sub

    'Thumbの中のCanvasの中のRectとtextBlockを60度回転させて表示
    Private Sub AddThumbRotateRect()
        Dim t As Thumb = GetThumb()
        Dim c As Canvas = t.Template.FindName("cc", t)
        Dim r As New Border With {
            .Background = Brushes.Cyan, .Width = 100, .Height = 100}
        Dim tb As New TextBlock With {
            .Text = "Thumbの中のCanvasの中のRectとtextBlockを60度回転",
            .TextWrapping = TextWrapping.Wrap,
            .Width = r.Width}
        t.Width = r.Width
        t.Height = r.Height
        c.Children.Add(r)
        c.Children.Add(tb)
        canvas1.Children.Add(t)
        SetLocate(t, New Point(350, 100))
        'Thumbの中のCanvasの中のRectとtextBlockを回転
        r.RenderTransform = GetTransformGroup(60, 1)
        r.RenderTransformOrigin = New Point(0.5, 0.5)
        tb.RenderTransform = GetTransformGroup(60, 1)
        tb.RenderTransformOrigin = New Point(0.5, 0.5)
        AddHandler t.DragDelta, AddressOf ThumbDragDelta
    End Sub

    Private Sub MainWindow_ContentRendered(sender As Object, e As EventArgs) Handles Me.ContentRendered
        'MsgBox("contentrendered!")
    End Sub

    Private Sub MainWindow_Loaded(sender As Object, e As RoutedEventArgs) Handles Me.Loaded
        Call AddThumbRotateThumb()
        Call AddThumbRotateCanvas()
        Call AddThumbRotateRect()

    End Sub
End Class

Wpf_test121_コントロールテンプレートControlTemplate - Visual Studio Team Services
https://gogowaten.visualstudio.com/WPF/_git/WPF_test7?path=%2FWpf_test121_%E3%82%B3%E3%83%B3%E3%83%88%E3%83%AD%E3%83%BC%E3%83%AB%E3%83%86%E3%83%B3%E3%83%97%E3%83%AC%E3%83%BC%E3%83%88ControlTemplate&version=GBmaster&_a=contents