code: def show(self):
          
          top = self.get_top_widget()
          if isinstance(top, (list, tuple)):
              for t in top:
                  if t is not None:
                      t.show()
          elif top is not None:
              top.show_all()
docs: Call `show()` on each top widget or `show_all()` if only one is known.
          Otherwise does nothing.