code: def restore_defaults_ratio(self):
          
          # Set the flag to true because user ask to.
          self.is_restore_default = True
          # remove current default ratio
          for i in reversed(list(range(self.container_layout.count()))):
              widget = self.container_layout.itemAt(i).widget()
              if widget is not None:
                  widget.setParent(None)
  
          # reload default ratio
          self.restore_default_values_page()
docs: Restore InaSAFE default ratio.