Windows 8 でタッチ操作でグリッドをスクロールしたときに描画がズレる。（最後が隠れる）

Private Const WM_VSCROLL As Integer = &H115
Private Const SB_THUMBPOSITION As Integer = &H4
Private Const SB_THUMBTRACK As Integer = &H5

<System.Runtime.InteropServices.DllImport("user32")> _
Private Shared Function PostMessage(hWnd As IntPtr, Msg As Integer, wParam As IntPtr, lParam As IntPtr) As Integer
End Function

Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
    MyBase.WndProc(m)

    If m.Msg = WM_VSCROLL Then
        If Me.LoWord(CLng(m.WParam)) = Me.LoWord(CLng(SB_THUMBPOSITION)) Then
            MyBase.BeginInvoke(New Action(Of IntPtr, IntPtr)(Sub(WParam As IntPtr, LParam As IntPtr)
                Dim testWParam As IntPtr = New IntPtr(5)
                DataGridviewEx.PostMessage(MyBase.Handle, 277, testWParam, LParam)
            End Sub), New Object() {m.WParam, m.LParam})
        End If
    End If
End Sub

Protected Function LoWord(input As Long) As Short
    Return CShort((CInt(input) And 65535))
End Function