/// <summary>
 /// Add the renderable group to the layer.
 /// </summary>
 /// <param name="group"></param>
 public void AddGroup(RenderableGroup group)
 {
     AllRenderables.AddSubnode(group.Name, group);
 }
 /// <summary>
 /// Add the renderable group with the given name to the layer.
 /// </summary>
 /// <param name="name"></param>
 /// <param name="group"></param>
 public void AddGroup(string name, RenderableGroup group)
 {
     AllRenderables.AddSubnode(name, group);
 }
 /// <summary>
 /// Add an empty group with the given name to the layer.
 /// </summary>
 /// <param name="name"></param>
 public void AddGroup(string name)
 {
     AllRenderables.AddSubnode(name, new RenderableGroup(UriUtilities.GetLastPart(name)));
 }