public void Refresh(IFileManager fileManager)
        {
            if (fileManager == null)
            {
                throw new ArgumentNullResourceException("fileManager", Resources.General_Given_Parameter_Cannot_Be_Null);
            }

            Type t = fileManager.RefreshType(Subject.AssemblyQualifiedName, Subject.AssemblyFileName);
            IVisualisableTypeWithAssociations subject = fileManager.RefreshSubject(t);
            Clear();
            AssignDiagramData(subject);
            Dispatcher.BeginInvoke(() =>
                {
                    PositionDiagramElements();
                    RaiseExpandCanvasRequested();
                },
                                   DispatcherPriority.ContextIdle);
        }