static void ShowWindow()
    {
        TransferFunction2DEditorWindow tf2dWnd = (TransferFunction2DEditorWindow)EditorWindow.GetWindow(typeof(TransferFunction2DEditorWindow));

        if (tf2dWnd != null)
        {
            tf2dWnd.Close();
        }

        TransferFunctionEditorWindow wnd = (TransferFunctionEditorWindow)EditorWindow.GetWindow(typeof(TransferFunctionEditorWindow));

        wnd.Show();
    }
    static void ShowWindow()
    {
        TransferFunctionEditorWindow wnd = (TransferFunctionEditorWindow)EditorWindow.GetWindow(typeof(TransferFunctionEditorWindow));

        wnd.Show();
    }