code: def reload_erase_combos(self, btn=None):
          
          # backspace erase binding
          combo = self.get_widget('backspace-binding-combobox')
          binding = self.settings.general.get_string('compat-backspace')
          for i in combo.get_model():
              if ERASE_BINDINGS.get(i[0]) == binding:
                  combo.set_active_iter(i.iter)
                  break
  
          # delete erase binding
          combo = self.get_widget('delete-binding-combobox')
          binding = self.settings.general.get_string('compat-delete')
          for i in combo.get_model():
              if ERASE_BINDINGS.get(i[0]) == binding:
                  combo.set_active_iter(i.iter)
                  break
docs: Read from dconf the value of compat_{backspace,delete} vars
          and select the right option in combos.