MapGraphicLayer provides a lightweight and inexpensive way to display additional information on top of all MapLayers including annotation layers. Both Sketch and Selection graphic layers are good examples of this type of use. Similar to the MapLayer, the data shown with a MapGraphicLayer should not be continously changing, which would cause the screen to be refreshed and redrawn.

You can subclass a MapGraphicLayer and inform the map when it needs to redraw because its content may have changed. But keep in mind that, in such cases, you should use the protected method RaiseDataChanged and pass a DataChangedEventArgs with the envelope of the area that needs to be updated. The map will decide if a refresh is necessary. Do not try to call Map.Invalidate or Map.Refresh too often because these could be CPU intensive operations, that will slow your application.

System.Object
   ESRI.ArcGIS.Mobile.WinForms.MapGraphicLayer
      ESRI.ArcGIS.Mobile.WinForms.SketchGraphicLayer

Target Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, Windows Vista, Windows Server 2008 family

Reference