I cannot add a shadow to the rings. They extend to the edges of the canvas. If I add shadows, then they will be off-canvas on the vertical and horizontal edges. The shadows would only exist in the "corners" of the rings.
But I am happy with 4.5.
I am not a fan of shadows. I create my icons many times for my own use. I am a big user of docks. Often, docks will automatically create a shadow or reflection of the icon for me. There may be times when I do not want a shadow. It is easier to find a tool to create a shadow automatically than it is to find a tool to remove a shadow.