public void SaveSelections(IEnumerable <QualifiedModuleName> modules)
        {
            _savedSelections.Clear();
            var openModules = _selectionService.OpenModules();

            foreach (var module in modules.Where(module => openModules.Contains(module)).Distinct())
            {
                var selection = _selectionService.Selection(module);
                if (selection.HasValue)
                {
                    _savedSelections.Add(module, selection.Value);
                }
            }
        }