public void MoveUpLayer(Layer layer)
{
    int index = Map.Layers.IndexOf(layer);
    if (index < 0)
        return;
    Map.Layers.RemoveAt(index);
    Map.Layers.Insert(index - 1, layer);
}
public void MoveDownLayer(Layer layer)
{
    int index = Map.Layers.IndexOf(layer);
    if (index < 0)
        return;
    Map.Layers.RemoveAt(index);
    Map.Layers.Insert(index + 1, layer);
}Yeah..indeed its a real pain of not having those SetZIndex and GetZIndex methods for the Graphics Layer.