### Godot version

4.1.1

### System information

linux

### Issue description

[simplescreenrecorder-2023-08-30_15.01.51.webm](https://github.com/godotengine/godot-proposals/assets/71937306/537d92b9-4f98-4fe6-adf4-71297be0471a)

I guess this wasn't the case before since I could save a layout named "2 monitors".

### Steps to reproduce

press space

### Minimal reproduction project

none
TreeItem *child_item = p_root_item->get_first_child();
	while (child_item) {
		child_item->set_checked(IMPORT_ITEM, true);
		if (p_select_with_data) {
			child_item->set_checked(IMPORT_ITEM_DATA, true);
		}
		_store_selected_item(child_item);
		_select_all_subitems(child_item, p_select_with_data);
		child_item = child_item->get_next();
	}
}
void ThemeItemImportTree::_deselect_all_subitems(TreeItem *p_root_item, bool p_deselect_completely) {
	TreeItem *child_item = p_root_item->get_first_child();
	while (child_item) {
		child_item->set_checked(IMPORT_ITEM_DATA, false);
		if (p_deselect_completely) {
			child_item->set_checked(IMPORT_ITEM, false);
		}
		_store_selected_item(child_item);
		_deselect_all_subitems(child_item, p_deselect_completely);
		child_item = child_item->get_next();
	}
}
void ThemeItemImportTree::_select_all_items_pressed() {