Gui: fix SelectionSingleton::checkSelection()
Gui: fix SelectionSingleton::checkSelection()

This affects sub-object selection detection

Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master