static void OnContextItem(MenuCommand command, SelectionMode mode)
        {
            GameObject[] selection = null;

            if (command == null || command.context == null)
            {
                // We were actually invoked from the top GameObject menu, so use the selection.
                selection = Selection.GetFiltered <GameObject>(mode);
            }
            else
            {
                // We were invoked from the right-click menu, so use the context of the context menu.
                var selected = command.context as GameObject;
                if (selected)
                {
                    selection = new GameObject[] { selected };
                }
            }

            if (selection == null || selection.Length == 0)
            {
                ModelExporter.DisplayNoSelectionDialog();
                return;
            }

            Selection.objects = CreateInstantiatedModelPrefab(selection);
        }