protected static void ModelPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        ReusableUIElement3D reusableElement = (ReusableUIElement3D)d;

        reusableElement.Visual3DModel = reusableElement.Model;
    }
    protected static void VisualPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        ReusableUIElement3D reusableElement = (ReusableUIElement3D)d;

        reusableElement.InvalidateModel();
    }