def on_accel_cleared(self, cellrendereraccel, path):
        """If the user tries to clear a keybinding with the backspace
        key this callback will be called and it just fill the model
        with an empty key and set the 'disabled' string in dconf path.
        """
        dconf_path = self.store[path][HOTKET_MODEL_INDEX_DCONF]

        if dconf_path == "show-hide":
            # cannot disable 'show-hide' hotkey
            log.warn("Cannot disable 'show-hide' hotkey")
            self.settings.keybindingsGlobal.set_string(dconf_path, old_accel)
        else:
            self.store[path][HOTKET_MODEL_INDEX_HUMAN_ACCEL] = ""
            self.store[path][HOTKET_MODEL_INDEX_ACCEL] = "None"
            if dconf_path == "show-focus":
                self.settings.keybindingsGlobal.set_string(dconf_path, 'disabled')
            else:
                self.settings.keybindingsLocal.set_string(dconf_path, 'disabled')
If the user tries to clear a keybinding with the backspace
        key this callback will be called and it just fill the model
        with an empty key and set the 'disabled' string in dconf path.