public static List <IDiagramEntity> GetImportantObjectsAt(this DiagramSurface surface, Point point)
        {
            var objects = new List <IDiagramEntity>();

            surface.GetShapesAt(point).ForEach(objects.Add);
            surface.GetConnectionsAt(point).ForEach(objects.Add);
            surface.GetConnectionPointsAt(point).ForEach(objects.Add);
            surface.GetConnectorEndPointsAt(point).ForEach(objects.Add);

            return(objects);
        }