Internal class encapsulating a layer item representing a map layer. This class manages the events coming from the layer and the legend refresh process.
Inheritance: ESRI.ArcGIS.Client.Toolkit.Primitives.LayerItemViewModel
		private void AddGroupChildLayers()
		{
			if (Layer is GroupLayerBase)
			{
				ObservableCollection<LayerItemViewModel> mapLayerItems = new ObservableCollection<LayerItemViewModel>();
				if ((Layer as GroupLayerBase).ChildLayers != null)
				{
					foreach (Layer layer in (Layer as GroupLayerBase).ChildLayers.Where(l => l.ShowLegend))
					{
						Layer layerToFind = layer;
						MapLayerItem mapLayerItem = LayerItems == null ? null : LayerItems.FirstOrDefault(item => item.Layer == layerToFind) as MapLayerItem;

						if (mapLayerItem == null || mapLayerItems.Contains(mapLayerItem)) // else reuse existing map layer item to avoid querying again the legend and lose the item states (note : contains test if for the degenerated case where a layer is twice or more in a group layer)
						{
							// Create a new map layer item
							mapLayerItem = new MapLayerItem(layer) { LegendTree = this.LegendTree, LayerItemsOptions = LegendTree.LayerItemsOptions};
							if (_dispatcher != null)
								_dispatcher.BeginInvoke(new Action(() => mapLayerItem.Refresh()));
							else
								mapLayerItem.Refresh();
						}
						mapLayerItems.Add(mapLayerItem);
					}
				}
				LayerItems = mapLayerItems;
#if !SILVERLIGHT
				// Don't display the AcceleratedDisplayLayers root node
				if (Layer is AcceleratedDisplayLayers)
					IsTransparent = true;
#endif
			}
		}
		private void AddGroupChildLayers()
		{
			if (Layer is GroupLayer)
			{
				ObservableCollection<LayerItemViewModel> mapLayerItems = new ObservableCollection<LayerItemViewModel>();
				if ((Layer as GroupLayer).ChildLayers != null)
				{
					foreach (Layer layer in (Layer as GroupLayer).ChildLayers)
					{
						Layer layerToFind = layer;
						MapLayerItem mapLayerItem = LayerItems == null ? null : LayerItems.FirstOrDefault(item => item.Layer == layerToFind) as MapLayerItem;

						if (mapLayerItem == null || mapLayerItems.Contains(mapLayerItem)) // else reuse existing map layer item to avoid querying again the legend and lose the item states (note : contains test if for the degenerated case where a layer is twice or more in a group layer)
						{
							// Create a new map layer item
							mapLayerItem = new MapLayerItem(layer) { LegendTree = this.LegendTree };
							if (_dispatcher != null)
								_dispatcher.BeginInvoke(new Action(() => mapLayerItem.Refresh()));
							else
								mapLayerItem.Refresh();
						}
						mapLayerItems.Add(mapLayerItem);
					}
				}
				LayerItems = mapLayerItems;
			}
		}