code: def on_success(self, inv_plugin, emit_set_slot):
          
          self.dirty = set()
          self.apply(inv_plugin)
          for changed_slot in self.dirty:
              emit_set_slot(changed_slot)
docs: Called when the click was successful
          and should be applied to the inventory.
  
          Args:
              inv_plugin (InventoryPlugin): inventory plugin instance
              emit_set_slot (func): function to signal a slot change,
                  should be InventoryPlugin().emit_set_slot