Update: I actually had to change this so that it uses a LocalFeatureService with the EditorWidget. Here is the complete code: ArcGISLocalFeatureLayer arcGISLocalFeatureLayer = null;
LocalFeatureService lfs = new LocalFeatureService();
lfs.Path = @"C:\Data\tactical.mpk";
arcGISLocalFeatureLayer = new ArcGISLocalFeatureLayer(lfs, "Target");
// Set the ID.
arcGISLocalFeatureLayer.ID = "Target";
arcGISLocalFeatureLayer.Editable = true;
arcGISLocalFeatureLayer.ValidateEdits = true;
arcGISLocalFeatureLayer.AutoSave = true;
arcGISLocalFeatureLayer.MouseLeftButtonUp += new GraphicsLayer.MouseButtonEventHandler(arcGISLocalFeatureLayer_MouseLeftButtonUp);
// Define a SimpleRenderer with a SimpleMarkerSymbol to display each observation. Each observation
// will be a small red triangle.
ESRI.ArcGIS.Client.SimpleRenderer mySimpleRenderer2 = new ESRI.ArcGIS.Client.SimpleRenderer();
ESRI.ArcGIS.Client.Symbols.SimpleMarkerSymbol mySymbol2 = new ESRI.ArcGIS.Client.Symbols.SimpleMarkerSymbol();
System.Windows.Media.SolidColorBrush defaultBrush2 = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromArgb(255, 255, 0, 0)); //Red
mySymbol2.Color = defaultBrush2;
mySymbol2.Size = 8;
mySymbol2.Style = ESRI.ArcGIS.Client.Symbols.SimpleMarkerSymbol.SimpleMarkerStyle.Triangle;
mySimpleRenderer2.Symbol = mySymbol2;
arcGISLocalFeatureLayer.Renderer = mySimpleRenderer2;
arcGISLocalFeatureLayer.InitializationFailed += new System.EventHandler<System.EventArgs>(arcGISLocalFeatureLayer_InitializationFailed);
arcGISLocalFeatureLayer.Initialize();
// Add the local feature layer to the map. The map will handle the initialization of the layer.
map.Layers.Add(arcGISLocalFeatureLayer);
ESRI.ArcGIS.Client.Toolkit.EditorWidget editorWidget = null;
this.editorWidget = new ESRI.ArcGIS.Client.Toolkit.EditorWidget();
this.editorWidget.Margin = new Thickness(12, 50, 0, 0);
this.editorWidget.Map = map;
this.editorWidget.AutoSelect = true;
this.editorWidget.AlwaysDisplayDefaultTemplates = true;
this.editorWidget.VerticalAlignment = System.Windows.VerticalAlignment.Top;
this.editorWidget.HorizontalAlignment = System.Windows.HorizontalAlignment.Right;
this.editorWidget.ShowAttributesOnAdd = true;
this.editorWidget.Loaded += new RoutedEventHandler(editorWidget_Loaded);
this.editorWidget.DataContext = arcGISLocalFeatureLayer;
this.editorWidget.LayerIDs = layerIDs;
this.editorWidget.ApplyTemplate();
LayoutRoot.Children.Add(editorWidget);
When the app starts I can see the EditorWidget with a set of tools for editing but as soon as the app finishes loading the EditorWidget reverts to a tool that allows you to just select, unselect, etc.