### 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
LineEdit *le = Object::cast_to<LineEdit>(p_control->get_child(1));
	if (le->get_text().strip_edges().is_empty()) {
		return;
	}
	String new_name = le->get_text().strip_edges();
	if (new_name == p_item_name) {
		_item_rename_canceled(p_data_type, p_item_name, p_control);
		return;
	}
	EditorUndoRedoManager *ur = EditorUndoRedoManager::get_singleton();
	ur->create_action(TTR("Rename Theme Item"));
	switch (p_data_type) {
		case Theme::DATA_TYPE_COLOR: {
			ur->add_do_method(*edited_theme, "rename_color", p_item_name, new_name, edited_type);
			ur->add_undo_method(*edited_theme, "rename_color", new_name, p_item_name, edited_type);
		} break;
		case Theme::DATA_TYPE_CONSTANT: {
			ur->add_do_method(*edited_theme, "rename_constant", p_item_name, new_name, edited_type);
			ur->add_undo_method(*edited_theme, "rename_constant", new_name, p_item_name, edited_type);
		} break;
		case Theme::DATA_TYPE_FONT: {
			ur->add_do_method(*edited_theme, "rename_font", p_item_name, new_name, edited_type);
			ur->add_undo_method(*edited_theme, "rename_font", new_name, p_item_name, edited_type);
		} break;
		case Theme::DATA_TYPE_FONT_SIZE: {
			ur->add_do_method(*edited_theme, "rename_font_size", p_item_name, new_name, edited_type);
			ur->add_undo_method(*edited_theme, "rename_font_size", new_name, p_item_name, edited_type);
		} break;