public static void RenderBlurred(this DrawingContext dc, int width, int height, Rect targetRect, double blurRadius, Action <DrawingContext> action)
    {
        Rect        elementRect = new Rect(0, 0, width, height);
        Placeholder element     = new Placeholder(action)
        {
            Width  = width,
            Height = height,
            Effect = new BlurEffect()
            {
                Radius = blurRadius
            }
        };

        element.Arrange(elementRect);
        RenderTargetBitmap rtb = new RenderTargetBitmap(width, height, 96, 96, PixelFormats.Default);

        rtb.Render(element);
        dc.DrawImage(rtb, targetRect);
    }